The Beast chews through seven new PSUs

Years ago, it wasn’t uncommon to see enthusiasts running generic or case throw-in power supply units. Most wouldn’t be caught dead with one now, of course, but back then we had larger problems to deal with and precious few PSUs from which to choose. Fortunately, that’s no longer the case. The power supply market has been flooded with new entrants of late, with seemingly every company that caters to enthusiasts looking to jump on the bandwagon. These newcomers join a market teeming with mature players who have been honing their craft for a while, and the resulting selection can be a little overwhelming.

Finding a good PSU—or, more specifically, the best power supply—in a sea of largely look-alike competitors is no easy task, particularly when your needs are complex. On one hand, enthusiasts need plenty of wattage and clean power delivery to feed high-performance components. CPU power use may be falling, but GPU power consumption continues to rise, and you want to be sure there’s plenty of wattage in reserve to handle The Next Big Thing. At the same time, power efficiency has become an important consideration not only as a token effort to reduce one’s carbon footprint (which is really just a ploy to impress that cute, hippy barista at Starbucks), but because lowering power consumption reduces a system’s cooling load, allowing for quieter operation.

So which among the mob of new models on the market delivers the cleanest, coolest, quietest, and most efficient power? To find out, we’ve rounded up seven PSUs between 600 and 800W from BFG Tech, Enermax, ePower, Mushkin, OCZ, Thermaltake, and Zalman. We’ve thrown them all into the ring against not only our beastly load generator, but also our current favorite in this wattage range: PC Power & Cooling’s Silencer 750W. Read on to see if the goal posts have moved in our quest for the ultimate enthusiast power supply.

Lining up the competition

Power supply units have many important attributes, and we’ve whipped up a handy comparison chart that sums up some of the basics for the units we’ve assembled in this latest round-up.


Wattage

Cooling

Modular?

80 Plus?

Warranty

Price

BFG Tech ES-800 800W
800W 140mm bottom No Yes Lifetime*

ePower Thunder 650W
650W 120mm bottom No No 3 years
$130

Enermax PRO82+ 625W
625W 120mm bottom No Yes 3 years
Mushkin
XP-800AP 800W
800W 140mm bottom Yes No 5 years
OCZ
EliteXStream 800W
800W 120mm bottom No Yes 5 years
PC Power &
Cooling Silencer 750W
750W 80mm rear No Yes 5 years
Thermaltake
Purepower RX 600W
600W 140mm bottom Yes No 5 years
Zalman ZM-750HP
750W
750W 120mm bottom Yes Yes 3 years

We’ve limited the wattage range of this round-up to between 600 and 800W because that seems to cover the meat of the enthusiast PSU market. Enthusiast rigs that pull anywhere close to 600W—let alone 800W—may be rare in the wild, but with CrossFire and SLI multi-GPU schemes becoming more popular and graphics chip makers pushing for new PCI Express standards that support higher wattages, we think it’s prudent to have a reserve of untapped power. We also want to have the right mix of connectors available for future upgrades, and this class of PSU tends to have them. This wattage range is well beyond the capabilities of budget generic models, which is why you won’t find one of those included in the mix. Generic PSUs, it seems, aren’t generally available above 500W.

Even with a relatively tight output range, there’s still a 200W gap between our least and most powerful units, with plenty of models peppered in between. To ensure that lower-wattage units aren’t at a disadvantage against those more generously endowed, our test methodology pushes each PSU to its individual limits and is largely independent of output wattage.

Of course, there’s much more to a power supply than its output rating. Efficiency is also important, and the industry has come up with an “80 Plus” certification standard for models that convert at least 80% of the AC power they draw from a wall socket to DC juice that can be used by a PC’s internals. All but three of the PSUs we’ll be looking at today sport 80 Plus certification badges. Mushkin claims that its XP-800AP is more than 83% efficient, too, even though it doesn’t carry an official 80 Plus certification. Thermaltake’s Purepower RX, however, is only rated for 75% efficiency. ePower doesn’t even publish an efficiency spec for its Thunder PSU. We will, of course, be paying close attention to efficiency as we thrash each unit with our custom load generator.

Reliability is much more difficult to quantify than efficiency, but it’s certainly no less important. PSUs can wane over time, gradually allowing voltages to sag and ultimately compromising system stability. They can also flame out in spectacular fashion, taking down the rest of a system’s components in a puff of magic smoke. Warranty coverage isn’t a direct indicator of reliability, but without spending years testing each PSU, it’s the best we have. The units in this round-up are largely split between three- and five-year pacts. ePower, Enermax, and Zalman take the three-year route, while Mushkin, Thermaltake, OCZ, and PC Power & Cooling kick coverage up to five years. BFG Tech bucks convention with a lifetime warranty, but only if you register your PSU within 30 days or purchase; PSUs that aren’t registered only get a single year of coverage.

Cooling and cable configurations give PSU makers two additional avenues to set their products apart. Most manufacturers have settled on large, bottom-mounted fans to keep their PSUs cool, whether those fans are 120mm or 140mm in diameter. It will be interesting to see how these designs stand up to PC Power & Cooling’s old-school approach, which mounts a much smaller 80mm fan at the rear of the PSU. On the cabling front, only the Mushkin, Thermaltake, and Zalman units are modular designs. The rest rely on a big bundle of cables that can’t be pared down to suit an individual system’s needs.

Getting a grip on cabling

Wading through the tangled mess of cabling associated with modern power supply units can be a daunting task, but we’ve made sense of it all with a chart that outlines each PSU’s power plug payload.


Main power

Aux 12V

PCIe

4-pin peripheral

SATA

4-pin floppy

BFG Tech ES-800 800W
20/24-pin 4-pin, 8-pin 2 x 6/8-pin,
2 x
6-pin
6 6 2

ePower Thunder 650W
20/24-pin 4/8-pin 1 x 6/8-pin,
1 x
6-pin
6 4 2

Enermax PRO82+ 625W
24-pin 4/8-pin 2 x 6/8-pin,
2 x
6-pin
6 7 1
Mushkin
XP-800AP 800W
20/24-pin 4-pin, 8-pin 4 x 6/8-pin 6 4 2
OCZ
EliteXStream 800W
24-pin 8-pin 4 x 6/8-pin 8 8 1
PC Power &
Cooling Silencer 750W
24-pin 4-pin, 8-pin 2 x 6/8-pin,
2 x
6-pin
8 6 1
Thermaltake
Purepower RX 600W
20/24-pin 4-pin, 8-pin 3 x
6-pin
7 4 2
Zalman ZM-750HP
750W
20/24-pin 4-pin, 8-pin 1 x 6/8-pin,
1 x
6-pin
9 9 2*

Hybrid connectors are all the rage these days, with PSU makers employing them on primary, auxiliary 12V, and PCI Express plugs. These connectors are great if you’re looking to maintain compatibility with older hardware, since they can easily be switched between different pin configurations. You’d be hard-pressed to find a reasonably recent enthusiast motherboard with a retro 20-pin primary power connector, so I wouldn’t worry about the lack of a hybrid primary power connector on the Enermax, OCZ, and PC Power & Cooling units. However, the OCZ’s 8-pin auxiliary 12V plug may not play nicely with motherboards that only have a 4-pin plug, with little clearance around it.

With graphics cards demanding ever more power, the number and type of PCI Express connectors has become increasingly important. Five of the units we’ve gathered today feature four PCIe power connectors, and among that group, only the Mushkin and OCZ units offer eight pins all around. The rest split PCIe power between two 6-pin connectors and two hybrid 6/8-pin ones. ePower and Zalman each offer a mix one 6-pin and one 6/8-pin connector, while Thermaltake’s Purepower RX has a trio of 6-pin plugs.

On the peripheral front, each PSU offers a unique mix of 4-pin, SATA, and floppy connectors. Zalman is easily the most generous here, although its two floppy ports come on an external splitter that will cost you one 4-pin peripheral connector. The EliteXStream comes a close second, offering not only eight 4-pin peripheral connectors, but eight SATA plugs as well. Curiously, most of the PSUs are actually biased towards providing more 4-pin power connectors than SATA ones, despite the fact that Serial ATA has not only completely taken over the hard drive market, but also made significant inroads among optical drives.

In previous round-ups, we’ve seen PSUs with modular cabling offer more cable leads than they can actually accommodate at the same time, giving users the ability to customize their unit’s connector bias. That isn’t the case with the modular units from Mushkin, Thermaltake, and Zalman, which don’t come with any extra leads. So, while you’re still free to remove unnecessary connectors to reduce clutter within an enclosure, there’s no provision to trade 4-pin peripheral connectors for more SATA plugs, or vice versa. That’s an unfortunate shortcoming, although it’s a limitation that obviously afflicts designs without modular cabling, as well.

Cable reach

Connector counts are only one part of a power supply’s cabling complement. Cable reach matters, too, particularly for those with full tower enclosures that separate system components across vast stretches of case real estate. Extra reach is also useful if you want to route cables carefully out of sight, lest a tangled mess of wires distract those peering through a case window from appreciating the painstakingly detailed guts of your system.

With the help of our trusty measuring tape, we’ve measured the maximum cable reach for each PSU. The reach measurements shown for SATA and four-pin peripheral connectors refer to the reach of the last connector on the longest cable.

OCZ’s EliteXStream easily offers the longest primary power connector, making it the best choice for upside-down enclosures that move the power supply far away from motherboard connectors. Most of the pack is bunched between 22.5 and 20 inches, which is still plenty of reach for most systems. Thermaltake and BFG pull up the shortest here with primary power connectors at 19 and 18.5 inches, respectively.

Auxiliary 12V reach is also an important consideration for the upside-down case crowd, and again, the EliteXStream offers the greatest cable length. ePower’s Thunder pulls up two-and-a-half inches short of the OCZ, followed closely by Enermax’s PRO80+. Again, the BFG ES-800 gets the short end of the stick, although this time its cable reach is within half an inch of three other units.

OCZ keeps rolling out cable as we switch to PCI Express power connectors, which stretch a full 25 inches from the EliteXStream. The PCIe leads on the Silencer and Thunder are nearly as long, and they run at least a couple of inches longer than the rest of the pack.

The EliteXStream has by far the longest reach on its 4-pin and SATA plugs, as well. With its closest rival a good seven inches behind, OCZ easily wraps this one up.

Looking at the rest of the field, the units from PC Power & Cooling and Mushkin seem to have the best balance of 4-pin and SATA connector reach. Thermaltake’s Purepower RX has an impressive 37-inch reach for its SATA plugs but only 26 inches for 4-pin connectors. ePower’s Thunder has a similar bias, but in reverse; its SATA plugs only reach up to 30 inches but 4-pin peripherals can be up to 35 inches away.

Rated capacities

We’ve already discussed the total output wattage rating of each of the power supply units in the spotlight today, but that’s only one component of the output rating story. Modern PSUs divide power across three main lines at 3.3, 5, and 12 volts, with each of those lines carrying a maximum current rating. As if that weren’t complicated enough, most PSUs also spread 12V power over multiple individual lines.


Maximum output current (Amps)


DC Output

+3.3V


+5V

+12V

BFG Tech ES-800 800W
30 30 22, 22, 36, 36

ePower Thunder 650W
24 24 20, 20, 20, 20

Enermax PRO82+ 625W
24 24 25, 25, 25
Mushkin
XP-800AP 800W
26 26 20, 20, 20, 20
OCZ
EliteXStream 800W
28 30 62
PC Power &
Cooling Silencer 750W
24 30 60
Thermaltake
Purepower RX 600W
30 28 18, 18, 18, 18
Zalman ZM-750HP
750W
30 30 20, 20, 20, 20

Most of these PSUs spread 12V power over three or four rails, usually with an identical maximum current rating for each. BFG Tech’s ES-800 is an exception, thanks to a 22A maximum current rating for two of its 12V rails and a beefier 36A rating for the others. Meanwhile, both OCZ and PC Power & Cooling eschew the idea of multiple rails completely. Instead, the EliteXStream and Silencer consolidate 12V power under a massive single rail. Mushkin’s XP-800AP can also be switched between single and quad-rail 12V modes, although we didn’t observe much of a performance difference between the two.

Don’t get too married to these current ratings, though; they’re only the tip of the iceberg. To get a handle on each PSU’s true capacity, we have to determine the maximum output wattage of each voltage line. The math is easy enough thanks to Ohm’s Law, which allows us to calculate wattage given voltage and amperage. However, power supply units with multiple rails are typically limited by how much power can be spread across those multiple lines—a total that’s usually less than the sum of each rail’s output capacity. Most PSUs also place limitations on how much power can be shared between the 3.3V and 5V lines. And then there’s the maximum output wattage across the 3.3, 5, and 12V lines, which often falls short of the PSU’s total output rating in order to reserve capacity for lesser-used voltage lines like the -12V and 5V standby rails.

To make sense of it all, we’ve put together a table showing the maximum output power for each PSU’s 3.3, 5, and 12V rails. Where applicable, we’ve also indicated the maximum combined 3.3 and 5V power, the maximum combined 12V power, and how much wattage the PSU can spread across all three main rails.


Maximum output power (W)


DC Output

+3.3V


+5V

+12V

BFG Tech ES-800 800W
99 150 264, 264, 432, 432
170 780
800

ePower Thunder 650W
79.2 120 240, 240, 240, 240
150 540
650

Enermax PRO82+ 625W
79.2 120 300, 300, 300
140 600
625
Mushkin
XP-800AP 800W
85.8 130 240, 240, 240, 240
160 768
800
OCZ
EliteXStream 800W
92.4 150 744
180
800
PC Power &
Cooling Silencer 750W
79.2 150 720
170
750
Thermaltake
Purepower RX 600W
99 140 216, 216, 216, 216
180 576
600
Zalman ZM-750HP
750W
99 150 240, 240, 240, 240
160 720
728

Sick of tables yet? I thought so. But bear with me, because maximum output power ratings tell us more about a power supply’s capabilities than anything else.

At the high end of the wattage spectrum, the units from BFG, Mushkin, and OCZ can deliver a full 800W across their 3.3, 5, and 12V rails. BFG’s ES-800 has the highest combined 12V output rating at 780W, followed closely by the Mushkin XP-800AP at 768W. However, it’s the EliteXStream that can support the heaviest combined 3.3 and 5V loads at up to 180W.

In the middle of the range we’ve assembled, the 750W models from OCZ and Zalman offer the same 720W maximum 12V output capacity. The ZM-750HP’s combined 3.3, 5, and 12V output is limited to only 728W, though, and its 160W combined 3.3 and 5V maximum falls 10W short the Silencer.

Turning our attention to entrants in the 600W range, the Thermaltake looks to be the most ambitious. The Purepower boasts a 576W maximum output on its 12V line and a whopping 180W of combined 3.3 and 5V capacity, despite having the lowest total output capacity of the bunch. Enermax has biased its PRO82+ towards 12V output capacity, where it can feed up to 600W, while ePower provides a little extra combined 3.3 and 5V power.

Loading up The Beast

A cornerstone of our power supply testing methodology is a custom-built load generator created by forum regular justbrewit that we like to call The Beast. If you’re unfamiliar with its frightening array of resistors, I strongly suggest checking out this page of our last PSU round-up, which details the rig’s internals and our testing methodology.

Behold The Beast!

We use The Beast to push each PSU to 25, 50, 75, and 100% of its output capacity while measuring DC voltage, AC ripple content, and gathering data that can be used to calculate overall efficiency. However, since The Beast is limited to applying loads in 2A increments, we borrow a page from The Price is Right and use amperage loads that come as close as possible to our targets without going over. The chart below shows the amperage loads applied to each PSU.


Total loads (Amps)

25%

50%

75%

100%

3.3V

5V

12V

3.3V

5V

12V

3.3V

5V

12V

3.3V

5V

12V

BFG Tech ES-800 800W
4 4 12 8 8 26 12 12 40 16 16 54

ePower Thunder 650W
4 4 10 8 8 20 12 12 30 16 16 42

Enermax PRO82+ 625W
2 2 10 6 6 20 10 10 30 14 14 42
Mushkin
XP-800AP 800W
4 4 12 8 8 26 12 12 40 16 16 54
OCZ
EliteXStream 800W
4 4 12 8 8 26 12 14 40 18 18 52
PC Power &
Cooling Silencer 750W
2 4 12 6 8 24 10 14 36 14 18 50
Thermaltake
Purepower RX 600W
4 4 8 8 8 18 12 12 28 16 16 38
Zalman ZM-750HP
750W
2 2 12 6 6 24 10 10 36 14 14 48

When testing with The Beast, each power supply was hooked up using its primary and auxiliary 12V connectors, two PCIe power connectors, and six four-pin peripheral connectors. We used a Pico ADC-212 digital oscilloscope to probe the 3.3 and 5V wires on the primary power connector. 12V lines were probed in the primary power connector and also with one of the PCIe power connectors. In the graphs on the following pages, 12V power from the primary connector will be marked 12V1, while power from the PCIe connector will be 12V2.

Apart from additional testing at 25% capacity, our methodology is largely identical to what was used in our last PSU round-up. However, we have tweaked our efficiency calculations a little to use actual average DC voltages along the 3.3, 5, and 12V (from the primary power connector) instead of arbitrary 3.3, 5, and 12V values. That should give us more accurate results and compensate for any voltage sagging under load.

Our testing methods

Testing was conducted in two parts. First, PSUs were run in the system detailed below for a series of power draw, temperature, and noise level tests. They were then hooked up to The Beast to test power delivery and overall efficiency.

All tests were run three times, and their results were averaged.

Processor

Athlon 64 X2 5000+ 2.6GHz
System bus HyperTransport
16-bit/1GHz
Motherboard

Asus M2N32-SLI Deluxe Wireless Edition
Bios revision 0906
North bridge nForce 590 SLI SPP
South bridge nForce 590 SLI MCP
Chipset drivers ForceWare 9.35
Memory size 1GB (2 DIMMs)
Memory type

Corsair CM2X512A-5400UL

DDR2 SDRAM at
742MHz
CAS latency
(CL)
5

RAS to CAS delay
(tRCD)
5
RAS precharge
(tRP)
5
Cycle time
(tRAS)
12
Audio codec Integrated nForce
590 SLI/AD1988B with 5.10.1.4530 drivers
Graphics 2 x

GeForce 8800 GTS 640MB
with ForceWare 162.18 drivers

Hard drives
2 x

Western Digital Caviar RE2 400GB
SATA

OS


Windows XP Professional

OS updates
Service Pack 2

We used the following versions of our test applications:

The test systems’ Windows desktop was set at 1280×1024 in 32-bit color at an 85Hz screen refresh rate. Vertical refresh sync (vsync) was disabled for all tests.

All the tests and methods we employed are publicly available and reproducible. If you have questions about our methods, hit our forums to talk with us about them.

BFG Tech’s ES-800 800W
Love you lifetime

Manufacturer BFG Tech
Model ES-800 800W
Price (Street)
Availability Now

Already well-known to PC enthusiasts, BFG Tech recently entered the power supply market and now has no fewer than ten different models on offer. The ES-800 is the latest, and as its name not so subtly implies, it’s rated for a maximum output of 800W. BFG’s trademark lifetime warranty is by far this unit’s most unique feature, though. This is the first time we’ve seen lifetime coverage offered with a power supply, and although BFG cuts the warranty to a single year if you don’t register within 30 days of purchase, online registration isn’t much of a chore. The relative value of a lifetime warranty for a product whose realistic useful life may not stretch beyond five years is debatable, however. 800W may indeed prove to be enough power for years to come, but as we saw with the transition to 24-pin primary power plugs, any major shift in connector standards could quickly render current PSUs obsolete.

BFG is quick to point out that there’s more to the ES-800 than just a long warranty. The unit uses rather nebulous “frequency conversion technology” to improve efficiency at lower load levels. PSUs are typically inefficient under loads far below their maximum wattage rating, and BFG says the ES-800 is at least 80% efficient all the way down to just 10% of its total output potential.

A massive 140mm fan keeps the ES-800 cool with plenty of venting at the rear of the unit. The cables are neatly sheathed from end-to end, and a flat grey finish completes the decidedly stealthy package. According to BFG, the ES-800 also makes use of Japanese-made capacitors throughout.

The ES-800’s DC voltage regulation looks quite good, with 3.3, 5, and 12V output all well within acceptable tolerances. Delivered voltages do start to slide as the load increases, but not by margins that would give us pause.

Although AC ripple content jumps around a bit and is notably more prevalent on the 3.3V line, there’s very little of it overall. At worst, just one one-hundredth of a volt’s worth of AC content sneaks into the ES-800’s DC feeds.

True to BFG’s promise, the ES-800 maintains at least 80% efficiency across all four of our load levels. The PSU is at its most efficient with our relatively modest 25% load, where it’s an impressive 87% efficient. Efficiency drops by about 2% with each 25% load step.

Enermax’s PRO82+ 625W
Worth the premium?

Manufacturer Enermax
Model PRO82+ 625W
Price (Street)
Availability Now

If judged purely on watts per dollar, Enermax’s $142 PRO82+ 625W offers relatively poor value. That’s an awful lot to ask for a 625W power supply that only comes with three years of warranty coverage. But then Enermax has been building PSUs for a long, long time now. Maybe there’s something to the PRO80+ to justify the cost. The use of 100% Japanese-made capacitors is certainly a good start, but it’s only a start.

According to Enermax, the appropriately-named PRO82+ can maintain at least 82% efficiency with loads between 20 and 100% of its maximum capacity. In fact, Enermax says the PRO is up to 88% efficient, which would be an impressive feat indeed.

At first glance, the PRO looks like any other enthusiast PSU. Its cables are sheathed, although not all the way, which looks a little cheap next to the full end-to-end coverage available on most of the PRO’s rivals. Enermax does provide handy velcro ties on the ends of each of the PSU’s PCI Express power connectors, though, and four additional Velcro cable ties are included in the box. That should help you keep the inside of your system looking neat and tidy, at least.

Flipping the PRO over reveals a 120mm cooling fan and plenty of venting at the rear. This is a standard cooling configuration for most new PSUs, with manufacturers tending to differ only on fan size. Enermax goes a little further here, employing a patented and apparently more aerodynamic AirGuard inlet shape that supposedly lowers noise levels by up to two decibels. The PRO’s fan speeds have been optimized for quiet operation, too. We’ll see how those optimizations shake out a little later when we bust out our sound level meter.

The PRO82+ generally errs on the side of providing slightly higher voltages than necessary, but its 3.3, 5, and 12V values are still solidly within tolerances across all four load levels.

Our ripple results are a little more intriguing, as AC content practically disappears from the 3.3 and 5V lines under 25% and 100% loads. The 12V ripple stemming from the primary power connector is also lower at those extremes, while AC content on the 12V PCI Express line is consistently higher. Overall, though, we’re still looking at only 13 millivolts worth of AC ripple content at worst, and that’s practically nothing.

Although the PRO80+ boasts an impressive 90% efficiency at our lowest load level, it dips just below 80% when run under full load. Efficiency drops by seven percentage points as we move from 25 to 50% load, too.

ePower’s Thunder 650W
New face, good PSU?

Manufacturer ePower
Model Thunder 650W
Price (Street) $130
Availability Now

Although new to us here a TR, ePower has actually been selling PSUs since 1990. A quick trip to the company’s web site reveals a staggering selection of different models aimed at servers, Micro ATX systems, and standard desktops. ePower’s PSUs seem to be widely available, too, with Newegg stocking several flavors, including this Thunder 650W model.

With a street price of just $130 at Newegg, the Thunder is one of the least expensive PSUs in this round-up. Of course, at only 650W, it’s also one of the least powerful. ePower’s three-year warranty doesn’t help matters much, either.

The Thunder makes up some ground on the aesthetic front, with a grey motif polished to a near-mirror finish. ePower has also done well to sheath nearly all of the PSU’s cabling end-to-end.

As one might expect, the Thunder features ample rear venting and a bottom-mounted fan—in this case, a 120mm unit. ePower provides a little something extra at the rear, too: a six-pin plug that looks not unlike a PCI Express power connector. Although the Thunder isn’t a modular design, this external plug hooks into an extension cable that features USB and Serial ATA power ports. These ports can supply juice even when the system is turned off, making the USB connection ideal for charging cell phones, MP3 players, and other devices. Having external Serial ATA power is a nice touch, too, particularly given the prevalence of eSATA ports on modern motherboards.

The Thunder 650W may not deliver the most accurate voltages of the lot, but the values are pretty consistent across our 25, 50, 75, and 100% load levels, and they’re all within acceptable ranges. We haven’t seen many PSUs exceed their advertised DC voltage tolerances.

Our AC ripple results are often within acceptable limits, too, and the Thunder is no exception. On its 12V PCIe rail, the Thunder does have more AC content than the BFG and Enermax units we’ve examined thus far, but at worst, you’re still looking at less than 200 millivolts. It is worth noting, however, that AC ripple on the 3.3, 5, and primary 12V lines increases with the PSU load.

ePower doesn’t publish efficiency numbers for the Thunder 650W, and the PSU isn’t 80 Plus-certified. Looking at our efficiency results, it’s easy to see why. Sure, the Thunder manages greater than 80% efficiency up to a 75% load, but when pushed to its limits, efficiency drops to below 74%.

Mushkin’s XP-800AP 800W
Another memory maker dips in

Manufacturer Mushkin
Model XP-800AP 800W
Price (Street)
Availability Now

With fellow memory makers Corsair and OCZ already knee-deep in the power supply market, it’s only fitting that Mushkin has decided to get its feet wet, as well. The company’s power supply lineup consists of five models, capped by the flagship XP-800AP. At just under $170 online, the XP-800AP is the priciest PSU in this comparo, and with 800 watts at its disposal, it’s also one of the most powerful. Mushkin hasn’t skimped in the warranty department, either; the XP-800AP is covered for five years.

Of course, we’d expect a beefy output rating and lengthy warranty from a high-end PSU like the XP-800AP—that’s par for the course. But Mushkin didn’t set out to build just another me-too PSU. The company has taken a slightly different approach with the XP-800AP, allowing users choose whether to feed 12V output through a massive single rail or spread it evenly across four voltage lines.

The debate over whether 12V power is best provided through a single rail or multiple lines has raged on for a while now, with PC Power & Cooling championing the former while much of the rest of the market rallies around the latter. Mushkin lets you choose sides via a simple toggle switch at the back of the PSU, and you can switch teams whenever you’d like. It’s a neat trick, but based on our own testing, there doesn’t seem to be much of a performance difference between the two modes. All the results you’ll see for the XP-800AP were collected with the PSU configured in single-rail mode.

While the XP-800AP’s 12V toggle is certainly a novel feature, Mushkin’s approach to the rest of the PSU is a little more conventional. That’s not necessarily a bad thing, though. A big 140mm fan keeps things cool, and there’s little to restrict airflow at the rear. Mushkin’s taken the modular path, too, which means your case won’t be cluttered up with a bundle of unused cabling.

Full sheathing keeps the cables you do use nice and tidy. I suppose the sheathing also has some aesthetic appeal, preventing a mess of red, and yellow wires from disrupting the XP-800AP’s otherwise reserved black and grey attire.

The XP-800AP’s DC voltages look good, with even the most extreme deviations within 2% of the target voltage.

Ripple looks to be a little more problematic for Mushkin, with AC content increasing as our test load scales up to 100%. We’re still looking at less than 22 millivolts at worst, though, and that’s quite reasonable.

The XP-800AP’s efficiency is more of a concern. Everything looks good under 25 and 50% loads, where the unit largely lives up to Mushkin’s efficiency claims. However, efficiency continues to drop as we push harder, bottoming out at just over 76%.

OCZ’s EliteXStream 800W
PCP with a twist of OCZ

Manufacturer OCZ
Model EliteXStream 800W
Price (Street)
Availability Now

OCZ purchased PC Power & Cooling a little more than a year ago, and the new EliteXStream 800W looks to have benefited greatly from that acquisition. This is the first OCZ power supply we’ve seen that has unmistakable PC Power & Cooling DNA—a single, massive 12V rail that in this case has a monstrous 744W output capacity. The EliteXStream clearly means business, then, and the 800W unit we’re looking at today is actually the baby of the line. OCZ also makes a kilowatt EliteXStream unit should your wattage requirements exceed a mere 800W.

PC Power & Cooling’s influence can clearly be seen in the EliteXStream’s design, but the boutique PSU maker’s notoriously high prices aren’t as evident. You can pick up an EliteXStream for as little as $150 online, which is actually less than you’ll pay for the other 800W PSUs in this round-up.

Not content to let its latest acquisition influence only the guts of the EliteXStream, OCZ appears to have let PC Power & Cooling take care of the decorating, too. The unit is surprisingly restrained considering OCZ’s penchant for bling. Only green LED lighting breaks up what otherwise is an all-black affair. I do quite like the stealthy look, especially since there are no polished surfaces to attract fingerprints.

For all its PC Power & Cooling influence, the EliteXStream doesn’t rely on a rear-mounted 80mm cooling fan. Instead, OCZ joins the new millennium with a much larger 120mm fan mounted at the bottom while a drilled-out panel allows for airflow through the rear.

OCZ eschews the modular approach for the EliteXStream, instead tying the unit to a massive bundle of extremely long cables. The cables are sheathed, too, although only up to the first connector on each line.

The EliteXStream’s 3.3 and 5V lines are practically bang-on target across the board, but the 12V rails stray at both extremes of our load testing. Don’t worry about those extremes, though. At its worst, the EliteXStream’s 12V rail is still less than 3% off the mark.

It’s hard to get down on such a small DC voltage deviation when the EliteXStream’s AC ripple results look so good. Sure, we’ve seen other PSUs register lower ripple values here and there, but few can match the EliteXStream’s consistently low ripple content on each rail across all loads.

True to its 80 Plus rating, the EliteXStream delivers better than 80% efficiency in each of our load tests. In fact, efficiency never dips below 82%.

Thermaltake’s Purepower RX 600W
A prescription for pure power?

Manufacturer Thermaltake
Model Purepower RX 600W
Price (Street)
Availability Now

With “only” a 600 watt rating, the Purepower RX could be called the baby of this round-up. It’s certainly the cheapest product of the bunch, with a street price of just $105. At 600W, that translates to quite an impressive cost per watt. And there’s more. Thermaltake hasn’t skimped in the warranty department, delivering five years of coverage despite the RX’s affordable price tag.

Surely Thermaltake has had to cut corners somewhere, and the Purepower’s lack of 80 Plus certification provides the first hint. The RX is only rated for 75% efficiency, putting it at a bit of a disadvantage against the competition. Efficiency isn’t everything, though, and the Purepower has other tricks up its sleeve.

A modular design is one of those tricks, and the Purepower practically looks naked without its associated cabling. This is a perfect example of just how much cable clutter can be eliminated with a modular PSU. The only leads permanently attached to the RX are 24-pin primary and 6-pin PCI Express connectors; the rest are added to suit your system’s power requirements. However, should those requirements demand an 8-pin PCIe power connector, you’ll have to look elsewhere. All three of the RX’s PCIe power leads are of the 6-pin variety.

Like many of its rivals, the Purepower relies on a single 140mm cooling fan and ample rear-panel venting. Thermaltake always seems to make its fan grills a little thicker than others, and that may impede airflow slightly. The integrated grill does give the RX a very clean look, though.

A big bundle of modular cables rounds out the RX, and their sheathing neatly extends all the way down to each power connector. Thermaltake also throws a rubber spacer into the box that sits between the PSU and case to help reduce noise generated by vibrations.

DC regulation isn’t a problem for the Purepower RX. Thermaltake keeps voltage rails consistently close to their targets across all four of our load levels.

AC ripple is very low on the RX, as well. The 12V PCIe line shows a little more AC content than the others with 25% and 50% loads, but it’s still quite good.

With Thermaltake only rating the RX for 75% efficiency, these results are perhaps better than expected. The Purepower maintains at least 80% efficiency up to a 75% load, but dips to under 76% efficiency when pushed to the limit.

Zalman’s ZM-750HP 750W
The quietest of them all?

Manufacturer Zalman
Model ZM-750HP 750W
Price (Street)
Availability Now

Although better-known for its ornate, exotic, and largely silent PC cooling accessories, Zalman has been in the power supply business for some time. It’s only fitting, then, that the company’s latest ZM-750HP PSU is billed as an ultra-silent offering. Building a quiet power supply is no easy task, and with 750 watts on tap, the ZM-750HP doesn’t hold back on the capacity front.

Zalman does hold back a little in the warranty department, though. Coverage is limited to three years. At least you’re not paying much of a premium here; the ZP-750HP can be had online for as little as $145—a reasonable price for a 750W unit.

Zalman knows cooling, and the company has selected a 120mm fan to move air through the ZM-750HP. There’s also a small heatpipe-fed radiator at the back of the unit, hiding just behind an open metal grill that allows for airflow through the rear.

Of the three modular PSUs in this round-up, only the Zalman hard-wires a string of Serial ATA power connectors to the PSU. That’s not an entirely bad idea, since there’s certainly no need for all cabling to be modular. Just about any modern system that necessitates a 750W PSU is going to need at least one Serial ATA power plug, anyway.

With just about every PSU maker offering sheathed cables, we’re forced to get a little picky here. Props to Zalman for sheathing all of its cables, including sections between connectors. However, that sheathing does pull up about an inch short of each connector. I’ll forgive that minor transgression because Zalman also throws a handy three-pin fan adapter into the box. This adapter plugs into a standard 4-pin power plug and provides a pair of three-pin fan connectors: one fed by the 5V line and another with 12V power.

That, folks, is a set of very accurate DC voltages.

The ZM-750HP keeps AC ripple content nice and low, as well. Curiously, ripple on the primary 3.3, 5, and 12V rails drops precipitously at full load, while the 12V PCIe line remains largely unaffected.

With at least 82% efficiency across the board, the ZM-750HP has no problem living up to its 80 Plus certification. In fact, the PSU’s 88.9% efficiency under our lightest load is nearly the highest power supply efficiency we’ve ever measured.

PC Power & Cooling Silencer 750W
An Editor’s Choice defends its crown

Manufacturer PC Power & Cooling
Model Silencer 750W
Price (Street)
Availability Now

An Editor’s Choice winner from our first PSU round-up with The Beast, PC Power & Cooling’s Silencer 750W has been our favorite high-end power supply for the better part of 10 months now. The Silencer delivers near-perfect power, and plenty of it, with low noise levels and high efficiency, making it a good benchmark for the new PSUs we’re looking at today.

The Silencer may not be the freshest model of the bunch, but it still looks to be a competitive option. A five-year warranty gets the Silencer off to a good start right out of the gate, and its $140 street price is really quite reasonable for a PSU that used to command upwards of $170.

Aside from its brilliant red paint job, the Silencer looks like pretty standard fare. A relatively small 80mm fan mounted at the rear takes care of cooling, and it works surprisingly well for the size.

Under the hood, the Silencer is anything but a traditional design. Rather than splitting 12V power between multiple rails, PC Power & Cooling uses a single, massive 12V rail with an impressive 60A output capacity.

Although delivered voltages are a little on the low side, particularly for the 5 and 12V lines, they barely waver as the load climbs from 25 to 100%. The Silencer’s DC voltages are all within less than 2% of their target values across the board.

This plot looks curiously similar to what we saw with the OCZ EliteXStream just a few pages back. AC ripple is incredibly consistent across the board.

We’ve seen a few PSUs in this round-up hit higher efficiencies than the Silencer at lower load levels, but few can match its 82% efficiency when pushed to the brink.

Efficiency

We don’t want to make too many direct comparisons between test results gathered from The Beast because each PSU was run under different loads corresponding to its individual specifications. However, efficiency is important enough to make an exception. Here we’ve graphed the efficiencies of each PSU at 25, 50, 75, and 100% capacity to see how they stack up against each other.

Our efficiency results are pretty close overall, but there are a couple of interesting trends worth pointing out. Notice how the efficiency spread is only about four percentage points with our 50 and 75% loads. That spread grows to closer to 10 points under 25 and 100% loads.

Lining up the competition on a single graph further illustrates just how close the contenders are, particularly in the middle of our load spectrum. The BFG ES-800, Zalman ZM-750HP, OCZ EliteXStream, and PC Power & Cooling Silencer stand out as particularly good candidates from an efficiency perspective. The BFG and Zalman units boast higher efficiencies at lower load levels, which is important if your system spends a lot of time idling, while those from OCZ and PC Power & Cooling fare a little better when pushed to their limits.

System temperatures

Our next batch of tests deployed the PSUs in a real-world system with a pair of GeForce 8800 GTS cards in SLI and a couple of hard drives. For these tests, the systems first sat at idle for 10 minutes. They were then subjected to a 10-minute load consisting of Prime95, Oblivion, and an IOMeter file server test pattern. Finally, the systems were allowed to idle for a 10-minute cool-down period.

System temperatures were measured using Everest Ultimate Edition.

With our test system idling, we have a temperature spread of no more than four degrees. The Zalman ZM-750HP emerges as the victor here, but only by a slim margin.

Most of our temperature deltas actually shrink when the test system is put under load, and again, the ZM-750HP looks very good. It’s still only marginally cooler than the competition, though.

This is the first time we’ve included cool-down results, and they provide some food for thought. For instance, look at just how much hotter the hard drives and motherboard run with our prized Silencer. The ZM-750HP isn’t nearly as impressive here as it was at idle and under load, either. Overall, though, we’re still only looking at a few degrees difference between the hottest and coolest temperatures for each component.

Noise levels

Noise levels were measured at idle and under load using an Extech 407727 Digital Sound Level meter placed 1″ from the rear of the system and out of the direct path of airflow. You’ll notice “missing” results for some of the PSUs at idle. We’ve omitted them because our meter only registers noise levels above 40 decibels, and most of the field is quieter than that at idle.

The Silencer and PRO82+ both prove inaudible to our sound level meter at idle, and the ES-800 isn’t far off the meter’s 40-decibel threshold. The PSUs from Zalman and OCZ do well here, too, while the ePower Thunder is more than two decibels louder than anything else.

Even with its old-school 80mm fan, the Silencer is still more than a decibel quieter than its closest rival under load. Zalman and BFG share second place here, followed very closely by Enermax’s PRO82+. At the louder end of the spectrum, ePower and Thermaltake swap places, with the latter generating the highest noise levels of the lot.

Power consumption

Power consumption was measured at the wall socket for the entire system, sans monitor or speakers.

There’s a 9-watt spread in our idle power consumption results, with the ES-800 taking top honors ahead of units from Enermax and Zalman. OCZ and Thermaltake fare the worst here. The EliteXStream’s result is particularly disappointing in light of its strong performance elsewhere.

Under load, the field splits into two packs. The three front-runners are led by Zalman’s ZM-750HP, and they have a healthy lead over the rest of the field. ePower’s Thunder proves to be the least efficient under load, pulling 30 more watts than the ZM-750HP.

Conclusions

I have to say this latest crop of PSUs has left me rather impressed. There really isn’t a lemon in the bunch, and while some models offer lower noise levels, higher efficiencies, and superior overall value, all managed to deliver consistent DC voltages with relatively little AC ripple right up to the limits of their rated capacities. We shouldn’t be surprised to see such a tight race, though. There may be eight different brands in this round-up, but in truth only a handful of companies actually manufacturer the PSUs we’ve tested today. That arrangement appears to have raised the bar for overall power supply quality, and that’s a good thing, even if it does leave us with a collection of largely similar designs that offer near-equivalent performance.

Because these PSUs—particularly the best ones of the bunch—offer such similar performance, we’ve been forced to pick favorites more on the basis of value, warranty coverage, noise levels, and little perks like modular cables. We’ve summed up our thoughts on each PSU below.

BFG Tech ES-800 800W — The ES-800’s lifetime warranty will no doubt impress some folks, but when it’s gated by a 30-day registration requirement, it loses some appeal for me. I’m also not sure just how much value lifetime coverage adds over, for example, a five-year warranty. Fortunately, the ES-800 has more to offer, including great performance and very low noise levels. The ES-800 is quite frugal, as well, boasting some of the highest efficiencies we measured under lighter loads. And even though $165 online this is one of the more expensive PSUs of the bunch, we think it’s TR Recommended material. Only relatively short cable reach—an important consideration for the larger enclosures that typically house systems that would require an 800W PSU—keeps the ES-800 from an Editor’s Choice award.

ePower Thunder 650W — The Thunder delivered clean power like the rest of the pack, but this unit’s $130 street price is simply too high in light of the competition. 650W isn’t a whole lot of capacity for the price, and ePower’s warranty is limited to three years when many of its rivals offer five years of coverage. The Thunder is quite loud, both at idle and under load, and its efficiency at 100% is the worst of the bunch. We do like the external SATA and USB power cable, but it’s just not enough in the face of such strong competition.

Enermax PRO82+ 625W — The PRO82+ is a very quiet power supply, and it’s one of only two in this round-up silent enough to dip below our noise level meter’s decibel floor at idle. This Enermax is also the most efficient PSU we’ve ever tested with a modest 25% load, and is quite efficient overall. However, our enthusiasm for this unit is tempered by its $142 street price, which only gets you 625 watts and three years of warranty coverage. There are better values in this bunch.

Mushkin XP-800AP 800W — As the most expensive PSU in this round-up, our expectations were high for XP-800AP. On the surface, this unit has a lot to offer, including modular cables with a whopping four 8-pin PCIe power connectors, a five-year warranty, and the ability to switch between single and multiple 12V rails. However, Mushkin has some work to do on the efficiency front; the XP-800AP dipped below 80% efficiency at not only full capacity, but also at 75%. We’d also like to see lower idle noise levels from the XP-800AP.

OCZ EliteXStream 800W — You can see the PC Power & Cooling breeding in OCZ’s new EliteXStream 800W, and that’s a very good thing. This PSU maintained at least 82% efficiency across all our test loads, and with impressive output capacity, four 8-pin PCIe power connectors, serpentine cables that can handle upside-down and larger enclosures with aplomb, the EliteXStream is well equipped for demanding high-end systems. A surprisingly low $150 street price also makes the EliteXStream the cheapest 800W PSU in this round-up, bringing it perilously close to Editor’s Choice distinction. However, a propensity for higher noise levels takes the EliteXStream down a notch; it’ll have to settle for TR Recommended status, instead.

PC Power & Cooling Silencer 750W — The Silencer earned an Editor’s Choice award a good 10 months ago, but is it still the daddy today? Much to our surprise, yes. The Silencer is still the quietest PSU in this class, with great power delivery and efficiency to boot. The competition has largely caught up on most fronts, and were the Silencer still selling for its original $170 asking price, we’d be less enthusiastic about it this time around. But the Silencer now costs just $140. When coupled with PC Power & Cooling’s solid reputation and five-year warranty, that’s good enough to retain its Editor’s Choice crown.

Thermaltake Purepower RX 600W — With a $105 street price, the Purepower RX is a good $35 cheaper than the next-closest PSU in this round-up. It also features the lowest output rating, and more seriously, lacks 8-pin PCI Express power plugs. The RX is one of the loudest PSUs we tested, and its efficiency drops below 80% when pushed to the limit. However, Thermaltake does kick in a five-year warranty and modular cabling. Those factors don’t make this our favorite of the bunch, but the Purepower is a good value.

PC Power & Cooling Silencer 750W
August 2008

Zalman ZM-750HP 750W — The ZM-750HP certainly lives up to its low-noise billing. More impressively, it’s one of the most efficient PSUs in the pack, particularly with light loads. And it doesn’t cost much, either; the ZM-750HP sells for just $145, which gets you clean power delivery and a huge bundle of modular cables. Unfortunately, those cables are poorly balanced. Zalman provides just two PCI Express connectors, only one of which can supply 8-pin power. That’s going to be a limitation down the line, and when coupled with Zalman’s three-year warranty, the ZM-750HP falls from Editor’s Choice candidate to TR Recommended.

Singling out Editor’s Choice winners is never easy, but PC Power & Cooling’s Silencer successfully defends its belt as the best enthusiast PSU with just the right balance of performance, silence, and price. Our contenders from BFG, OCZ, and Zalman are great options, too, and if you’re a stickler for warranty coverage, need long cables for a big enclosure, or want a modular design, one of ’em may be an even better choice for you than the Silencer.

Comments closed
    • tsoulier
    • 11 years ago

    Why leave out Corsair ??

    • Umbragen
    • 11 years ago

    Does anyone know what the differences are between the three Silencer 750 Quad’s currently on the market, besides color? The three sell at different prices and have inconsistent manufacturer designations. Are there mechanical reasons I should be willing to pay more for the newer blue model over the older red one?

      • Krogoth
      • 11 years ago

      I believe it is just certifications.

      The blue unit is SLI certified, the red unit is CF certified, while the black unit is the normal unit.

      They should all have practically identical performance and amount of plugs.

    • shank15217
    • 11 years ago

    Good review, however realistically why would anybody run their PSUs at near 100% load? Running the power supply so close to its rated capacity is just asking for eminent failure. Apart from an academic curiosity, I wouldn’t pick a power supply with the highest efficiency at 100% load but maybe at 75% or 50% load. I think the BFG unit is an overall better choice.

    • Firestarter
    • 11 years ago

    Just one thing that I’m curious about is the power consumed by these PSU’s at 0% load or at the minimal load of a PC on standby.

    Considering that a PC might spend 3/4 of its day on standby or turned off with the power still connected, these figures could have another measurable impact on total power consumption.

    • Aphasia
    • 11 years ago

    Just put together the new comp today, which i got a Corsair HX 520w for. It will be just fine. But i probably wont be able to run any Crossfire on it. Not with another 4870 anyway as they are around 174watts each. Had i gotten a 620w i could have.

    The funny thing was in the manual, where asus recommends at least a PSU on 600w for their mobo in a large notice. Of course, when one continues to read, they have then compare 3 packeges, the largest with a tricked out rig using 3 way 8800 SLI and 7 drives so…

    A small comp using a high-end cpu, high end graphics and a single drive can easily use a 500w without screaming. The worst thing is the second graphics card. Thats really the one that hits you bad.

    As for wires, my card came with a 2 x molex -> 6pin adapter. Two of those together with the two normal PSU leads would give give you 4 6pin leads to run SLI even though the CPU doesnt have enough PCIe-leads.

      • MrJP
      • 11 years ago

      I’ve got the same HX520W powering my 4850 Crossfire system without breaking a sweat. It’s drawing a peak of about 350W at the wall, so even assuming 85% efficiency the system is only drawing about 300W from the PSU. According to TR’s numbers, a 4870 Crossfire system uses about 85W more than 4850 Crossfire, so it could probably fairly comfortably cope with that as well. 700W-800W PSUs are just not necessary unless you’re going to 3+ GPUs.

        • Aphasia
        • 11 years ago

        Yeah, i went back and rechecked the numbers on the crossfire 4870 setup. 448 watts, but i missed the crucial thing… “At the wall”. 😉 Not that i would image doing 4870 crossfire anytime soon, but, who knows.

    • moritzgedig
    • 11 years ago

    I would have cared for the off-load.
    my new PSU takes 40W if the machine is off.
    That is 70 Euros for me per year. Unacceptable!
    I use a powersocketadapter with a powerswitch to adress this problem.
    Also I’m against the gigantomanie with PSUs, a 400W PSU is good enough for 99% of PCs.

      • liquidsquid
      • 11 years ago

      I agree, this is unacceptable. A properly designed supply will turn off the primary and leave a house-keeping supply on in this state, consuming much less power.

      It should be an easy enough test for the guys at TR to perform, and the first I have heard of “off” power consuming soo much.

      -LS

    • allston232
    • 11 years ago
    • computron9000
    • 11 years ago

    An easy analogy to the excessive PSU phenomenon would be this:

    Buy a car with 1,000 horsepower, but by design, the pedal cannot go down further than about 25% of the way to the floor. So you have all of this “capability” that simply cannot be accessed. It is easier on the engine and other parts to not drive beyond 25%, but there are better, cheaper options that fit more closely to what is needed.

    I think a lot of it has to do with e-peen stuff. “Well *MY* system needs a fricken KILLOTWATT PSU just to run !!!”

    I’m with Usacomp2k3 on this one. Liked the review and interesting points, so I’m not being critical of the subject matter (and it would be immensely useful if I was spending $2500 on a new computer right now, which I do every 3-5 years), but these PSUs *ARE* for super-high-end SLI systems or people that just want to say, “Well *I* have a 750 watt PSU! HAH!”.

    • Aphasia
    • 11 years ago

    Something i would also like to see just for the kicks is of the maximum power ability of today. How far can they really go before crankning out, shutting down or just explode. 😉 Of course, i can see why you might not want to do it, or actually, what it actually gives to do it as they all seem to clear their respective ratings. Could still be fun though 😛

    Although maybe that was just in the old that it was more critical when just everything was “generic” in one sense or another. Back in the old days i used a 250w Fortron source sparkle PSU that went quite abit higher than its rating. This at a time where some other PSU’s barely managed their rating. Mine came with the highly recommended fulltower Inwin Q500 and its removable motherboard tray. A favorite among overclockers and builders at the time.

    On a more serious note. Have you thought about testing the rated 100% load for each individual voltage rail to see that it works as specified as long as the total maxium wattage rating of the PSU isnt exceded?

    In this review accourding to the beast-settings table at 100% you barely got up to half the individual load on the 3.3v and 5v lines, compared what is specified. Although that would of course require lowering the 12v line abit for that test.

    Still, i havent read PSU-design, so it might not be something that is worth checking out. Or for that case, have an impact since nobody would ever skew the balance as much?

    • mattthemuppet
    • 11 years ago

    Nice review! I was quite surprised to see the shape of the efficiency curves for some of the PSUs – I’ve never seen on that starts high and then decreases before, usually they’re slightly bell shaped (low at low loads, rising to a peak ~50%, then dropping off slightly at full load). Any ideas? I thought it might be something to do with how the loads are configured, but it seems similarly balanced to other review sites such as SPCR.

      • Voldenuit
      • 11 years ago

      That’s because TR tests the loads too high to start with.

      Most systems with discrete GPUs draw around 100-125W at the PSU at idle. That’s 25% or lower on a 500W PSU, and 16% or lower on a 750W PSU.

      Considering usacomp2k3’s observation that most systems top out under 350W at the PSU, it seems to me as though the testing points that TR uses, while interesting from the perspective of PSU quality, are not representative of real world usage.

      Once we start testing from a lower draw, you will start to see the bell shape that you are more familiar with.

    • computron9000
    • 11 years ago

    In the next PSU review, I have a few suggestions to make that would bring up some interesting discussion points on the forums:

    1) Try to throw an “odd-ball” PSU into the mix. i.e. a really crappy generic brand or a super-high end PSU in with a bunch of budget-PSUs. These scenarios come up in the forums a lot and it would be interesting to have some results of what happens when you waste $140 on a PSU you don’t need or put a $15 PSU in a system that should have a $40-$60 PSU. For example, in the latest review I’d have been very interested to see how, say, a Seasonic S-12 450 PSU would have done with that test system. On the flipside, it would be neat to see a 1.1KW PSU lose in an idle efficiency test on a low-end computer.

    2) Have a special “load” category for Folding to see what kind of impact the PSU would have on annual bills for a folding machine.

    3) Make a chart that shows Cost Per Year in avg electricity to run at idle or load 24×7. Some PSUs pay for themselves within a year of usage.

    • Usacomp2k3
    • 11 years ago

    Where did you find a 5:4 CRT monitor to run at 1280×1024 @ 85hz?

    • LoneWolf15
    • 11 years ago

    Maybe I missed it (if so, my apologies, feel free to point it out), but I have a question: What temperature were these power supplies operating at when tested for efficiency under load?

    How warm a PSU gets can have a great effect on its efficiency. Some PSU’s can’t handle the heat over 40C, some high-end models are engineered to 50C, and some cheapies fall off prior to 40C. A well-ventilated case, or a poor one can make all the difference in how one of these units might hold up, so it’s a good thing to know.

    • Usacomp2k3
    • 11 years ago

    I hate to be a critic, but when your highest load measured was 380W and that’s with SLI and a power hungry motherboard, measuring the efficiency at anything more than 400W is useless. The most telling page on this review is the one that showed the actual power usage. I think those should be emphasized more. The Zalman 750W registered just 351W at full load. That’s under 50%. Why bother with high-wattage PSU’s? What a waste of money. Anyone who paid more for anything over 450W is wasting their money. Could there maybe do a review that shows power supplies that are not excessive for people? Otherewise they are appropriating their money incorrectly when it comes to buying a computer. $60 buys you a 550W Antec with all the cabling most people would need. Why would someone pay $130 for something that honestly isn’t going to provide you with anything better? $80 will put you a good way forward upgrading from a 22″ to a 24″ monitor which will last you alot longer than a PSU.

    EDIT: Don’t get me wrong. I thought the review was very well done. It just doesn’t apply to me nor would I necessarily recommend any of these PSU’s to people looking to build. There are PSU’s out that there that are just as good and are cheaper because they aren’t excessive.

    • frybread
    • 11 years ago

    Thanks, great review

    • emorgoch
    • 11 years ago

    The one thing that’s always missing from these PSU reviews (not just TR, but everyone) is how well they handle ripple in the AC input. Lots of people I know live in older neighborhoods and have to deal with a lot of variance on their AC lines. It would be really nice to see how well these PSUs handle AC inputs from 105V through to 125V.

      • indeego
      • 11 years ago

      Get a UPS. Made for such conditionsg{<.<}g

        • A_Pickle
        • 11 years ago

        You finish your posts with green punctuation. Why?

          • computron9000
          • 11 years ago

          The same reason you finish yours with black?

            • A_Pickle
            • 11 years ago

            …I, er… do?

    • JustAnEngineer
    • 11 years ago

    Did I miss a table that mentioned that the Silencer 750 is not an ATX power supply, but instead follows the EPS12V form factor, making it too deep for use in many cases?

    I’ll also mention from personal experience that the 24-pin cable on the Silencer 750 is too short to use in the Antec P182 case, so you’ll have to use an inefficient extension.

    • Kulith
    • 11 years ago

    great review!

    I have a question though, you keep pointing out how some cables are sheathed more so than other cables… and im still trying to figure out why it matters. Is it just for looks or what?

    Keep in mind that non-sheathed cables are much more flexible. For example, if you are hiding the cables behind the mobo tray and you are trying to bring the cable out from underneath and plug it in directly to the mobo a full 260 degrees, it would be easier to do with the cables that left a few inches unsheathed. Anyways, I dont think its particularly important at all that they be sheathed in the first place.

    Also, I agree with ssidbroadcast, I think modular cabling is very appealing when looking into a new psu. I think its more important than cable sheathing or cable length or the design/color of the psu….

    You mentioned that the BFG Tech ES-800 800W lost the editors choice award just because of cable reach, which I think is sort of a separate issue, if an issue at all. But i’ve never owned a full tower case so im speaking out of my experience box here. 18.5 inches and above seems like it should be plenty to me…but I duno I could be totally wrong.

    • CampinCarl
    • 11 years ago

    I have a question…when will TR review some more ‘mainstream’ PSUs? Something less than 600W, preferably less then 500W even? It’s not that I dislike these, it’s just that my personal build…uhh, tastes, tend to lend themselves to more lower-power systems (i.e. 1 graphics card on the lower edge of the midrange, low-end processor, etc.).

      • Dissonance
      • 11 years ago

      Stay tuned.

        • CampinCarl
        • 11 years ago

        Woot 🙂 Good to hear that!

        • Bauxite
        • 11 years ago

        Especially the $40/600W deal right now that has more than enough power to cover even say 95% of TR reader’s rigs…

        The day I got a UPS with a watt meter on its LCD was the day I wondered wtf I had been buying way overspec on my PSUs
        (I had an engineering grade VM for the longest time but never bothered to bring it home)

    • SpotTheCat
    • 11 years ago

    It’s too bad PSUs fail more than anything IME. I’d take a long warranty over any other features if I were in the market now, assuming this much similarity.

      • Saribro
      • 11 years ago

      And when they fail, they often take out other components along with them. I’ve had a PSU failure kill a motherboard and CPU all in 1 go, nasty situation :/.

      • KeillRandor
      • 11 years ago

      thankfully that hasn’t happened to me yet – (though I’m still using a Zalman 300w thats over 5-years old now). I’ve had two motherboards with dead IDE channels though – (that also took out my main HDD’s when they went, too 🙁 ).

    • ssidbroadcast
    • 11 years ago

    Boy am I 1sty…

    I didn’t know BFG made power supplies, so I guess it’s a good thing they made editor’s choice.

    Btw, Geoff, Bellingham WA is /[

      • Skrying
      • 11 years ago

      I disagree on modular PSUs being in general much more desirable. My current PSU is a modular unit and I really just wish it wasn’t. When it comes to cleaning up cables I find how modular cables come out across different points in the back of the PSU much more frustrating than having excess cables which can just be tightly bound up behind the motherboard tray or sometimes even above the PSU itself.

      Right now in my Antec P180B case I highly regret having bought a modular PSU. The bottom chamber fan just makes the experience painful. Having to complete remove the PSU from the case and redo all the wiring to add a cable makes me cry at night.

      Now on the other hand I’ve been really considering a Lian Li PC-A05B and it’s setup could potentially lend itself better to a modular unit, but I just don’t think its advantages and potential disadvantages make it a real deciding factor for me.

      So in summary, yes it can be a bonus. But I certainly don’t think it was enough of a bonus to make up for the PurePower RX’s otherwise relatively poor showing in this round up.

        • Bluekkis
        • 11 years ago

        It all comes down to what case you are using. I wouldn’t buy psu without modular cables, mainly because I’m finding it very problematic to stuff those insanely long cables on my small tower ( SilverStone SG03 ) even when I’m using only the cables I really need. With max length from psu to any component in case is about 20cm and front case fans only about 8cm away from psu, lots of long cables becomes very annoying.

          • Anomymous Gerbil
          • 11 years ago

          It’s a shame that PSUs with modular cables don’t offer several lengths of each cable type, or at least have them available as an option. Sure it would add a bit to the cost, but that would certainly make good use of the feature.

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