Single page Print

The Beast chews through seven new PSUs


The latest and greatest between 600 and 800W
— 10:52 PM on August 4, 2008

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.