Power supplies are generally not thought of as the most interesting PC components, but they can often be the most vital, especially for system stability when you’re pushing your hardware to its limits. You see, the power supply is responsible for keeping all of your PC’s flashy goodies fed with ample quantities of steady, clean power. Without a good power supply, your high-end system could be reduced to a mess of crashes and instability.
Over the years, I’ve seen numerous systems whose laundry list of problems were all remedied by swapping out an underpowered or low-quality generic power supply. Even the latest problems with ATI’s Radeon 9700 Pro have been attributed, by some, to poor quality and low-wattage power supplies in users’ systems. As our systems get more and more powerful, we’re going to need more and more clean, quality power to keep them running. Today we’ve rounded up four very different power supplies from Antec, Thermaltake, and Vantec. Which is easiest on your wallet and ears, and which is able to provide the most consistent power under load? Let’s get started and find out.
Both ends of the spectrum
Antec is well known for their full line of PC cases which we’ve previously reviewed. The nice thing about buying an Antec case is that you get an Antec power supply inside, which is one of the reasons I find myself recommending Antec’s cases over and over again, especially for consumers who may not be savvy enough to pick out a good power supply on their own. Far too often I see swank aluminum cases at local shops decked out with all sorts of eye candy, packed with generic, no-name power supplies that frankly, I just don’t trust on high-performance systems. We actually have a couple of Antec’s latest line of TruePower power supplies in house for this comparison, one comes in at 380W, and the other at 550W. Having two power supply models from the same manufacturer with differing wattage ratings will give us an opportunity to more directly compare wattage overall, since the Antec power supplies both share a common TruePower feature set.
Antec’s TruePower power supplies look, well, much like other power supplies. In addition to the standard rear 80mm exhaust fan, Antec sticks a second 90mm fan on what ends up being the bottom of the power supply. For whatever reason, the two fans are different colors, but you’ll have to peer beyond the fan grill to notice the difference.
Here’s a shot from the rear. You can see some additional venting on parts of the power supply that get decent airflow within the case, and you can see just how much space that 90mm fan takes up on a power supply of this size.
Power supplies generally offer temperature-controlled fans these days, but Antec claims its Low Noise Technology is better than the rest and results in lower operating noise levels than the competition. We’ll test that claim later on.
TruePower power supplies also have two special MOLEX connectors designed to work only with case fans. These additional connectors give the power supply control over the speed of your case fans, which will go up and down in line with what the power supply’s own fans are doing.
Antec doesn’t allow users to adjust fan speeds, so everything is controlled by the power supply’s thermal sensors. Power supply temperature isn’t necessarily an indicator of overall case temperature, so you might not want case fans positioned around something like your hard drives relying on the power supply to control their speed.
Believe it or not, I have not one, but two older Antec power supplies that don’t have their own power switches. Not having that switch can sometimes really be a pain, and I’m glad to see that Antec has one included on its TruePower series. I can’t tell you how many times I’ve had to yank the cord on my other Antec power supplies because I crashed a system on a testbed that didn’t have a normal power switch hooked up in the first place. Of course, not having a switch in the first place is my fault, but it’s nice to know that Antec’s new power supplies have my back now.
Despite their differing voltage ratings, the 380W and 550W TruePower units have the same number of MOLEX connectors and offer the same amount of cable reach for each. There’s nothing wrong with that, so long as there’s enough of each.
Seven MOLEX connectors and two FDD power connectors should be enough most systems, especially if you use the extra two fan-only MOLEX connectors that Antec provides. The power supplies’ MOLEX connector reach tops out at 32″, which should suit all but the tallest full tower cases, even if you’re running hard drives mounted at the bottom of the case where air tends to be the coolest. Finally, we have Antec’s sheathed motherboard power cord, which can reach power connectors a full 22 inches away from the power supply itself. The length is nice, and should be adequate for most case and motherboard setups. The sheathing itself is pretty slick, and the ends are nicely secured with heat shrink tubing, which puts a nice finishing touch on the whole package. Sheathing loose cables can really clean up internal cabling, which in turn can help out with air flow inside a case. A case’s internals also look a lot nicer with clean cable sheathing, if you’re into that sort of thing. If you’re trying to color-coordinate, at least the black sheath will hide the rainbow of wires that makes up a standard motherboard power supply cable.
550W is probably a waste for the vast majority of even enthusiasts’ high-end rigs, but there are plenty of mid-range power supplies with more timid, but sufficient, power ratings. In this comparison, we’re looking at Thermaltake’s latest Purepower 360W unit, and even though there’s really not much to a power supply, the Thermaltake unit manages to distinguish itself in a few areas. The Purepower 360W is also the lowest-rated power supply in our test, which should make stress testing quite interesting. I’m not lucky enough to have a multi-drive, SCSI-equipped, dual-Athlon test system, but as you’ll see later I did manage to assemble a nice stack of hardware for our stress tests. But back to the Purepower 360W, which is pictured below.
Wait, aren’t we missing a fan here?
The Purepower 360W’s most unique trait is its single-fan design, which eschews the second and sometimes third internal fans that some manufacturers are putting on their power supplies. Single-fan power supplies aren’t new by any stretch, and I’ve got a small collection of 200-250W power supplies that are years old and also feature only a single rear exhaust fan. However, I don’t think I’ve seen any 300W+ power supplies with only a single fan, and I wish you the best of luck getting all but the most bare systems stable on one of my old 250W power supplies.
Extensive venting is used throughout the Purepower 360W’s external casing to make up for the lack of a second fan, but I wouldn’t expect airflow within a case to be nearly as good with only a single exhaust fan spinning away. One benefit to a single-fan design is lower sound levels, however. All that internal venting should, for all intents and purposes, be silent when compared to the noise created by an auxiliary fan.
The real question, of course, is whether or not the single fan can keep the power supply cool enough under load, and whether the fan speeds necessary to do so with a single fan produce less noise than a dual-fan setup. We’ll get into some noise testing a little later, but it’s something to keep in mind as we discuss the power supplies.
I haven’t dealt with Thermaltake power supplies before, so I was relieved to find that Thermaltake does offer an external power switch on its Purepower 360W. And it’s a big sucker. There’s no way you’re going to miss this one, even if you do have to contort your body into an awkward position just to flail around behind your case in the hopes of hitting the switch.
I should note that the particular Purepower 360W power supply we’re testing features Thermaltake’s Passive PFC technology, which uses parallel capacitors to help regulate output current. All of the power supplies we’re testing today actually feature power correction technology, so Thermaltake doesn’t get a leg up on the competition in terms of features. However, since Purepower models are available with and without Passive PFC, it’s worth noting.
The Purepower 360W offers the lowest wattage rating of the power supplies we’re testing today, and it has the fewest number of MOLEX connectors to match.
There’s a total of six MOLEX connectors to play with, plus two connectors for FDD power. The MOLEX connectors have 28″ of working reach, so you shouldn’t have to worry about reaching all of your hard drives.
All the standard motherboard power plugs are there, but Thermaltake has left the motherboard power cable bare. Given that many of Thermaltake’s products are coolers and cases targeted at enthusiasts, I was expecting a sheath over the power cable, but all you get is a couple of zip-ties to hold things together along the cable’s 20 inches of bundled wire. The zip ties still hold the wires together, but it’s not the most elegant solution.
Back in black
The Vantec name rings familiar, but there’s a lot more going on here than simply slapping an extra letter on one of Antec’s power supplies. In fact, the Vantec Stealth 520W is the most unique power supply in this comparison. The Stealth 520W is targeted squarely at high-performance enthusiasts and overclockers with a sense of style, but that’s perhaps the most fickle crowd Vantec could possibly target. Gobs of power without a huge noise penalty are hard enough to balance, but throwing aesthetics into the mix makes things that much more difficult. Believe it or not, some people not only want, but demand personality, performance, and good looks. Greedy bastards. Can Vantec keep them satisfied with the Stealth 520W?
The first thing you’ll notice about the Stealth 520W is its all-black aluminum casing. The conductive properties of aluminum could give the Stealth 520W an edge when it comes to cooling, and no one can deny that the black just looks cool. Well, cool for something you’re going to bury inside your case and never see unless you have a case window. Thankfully, there’s more to the Stealth 520W than a slick exterior; this baby’s got substance, too.
Part of the Stealth 520W’s substance lies in its fansall three of them. The Stealth 520W is the only power supply in this comparison sporting three cooling fans, each of which measures 80mm in diameter. As part of its ode to aesthetics, the fan blades are translucent, and the grills nice and shiny. I was half expecting some really trick laser-cut custom fan grills on the Stealth 520W, at least for the rear exhaust fan.
With three fans spinning, the Stealth 520W should be able to keep itself cool and do a pretty effective job pulling rising hot air out of the top of your case. Three fans, however, aren’t going to be silent, but Vantec has that base covered.
Vantec provides a fan speed switch right on the back of the PSU to let you control the speed of all three fans at once. Unlike some power supplies, which Vantec points out only let you throttle the speed of the rear exhaust fan, Vantec’s switch affects all three of the power supply’s fans, though you can’t set the speed of each individually. Control over fan speeds can have a definite impact on overall noise levels, which will be especially useful for those living in cramped quarters who want to keep their systems crunching Folding@Home all night long and actually have the environment quiet enough to sleep in.
At the rear of the power supply, you’ll also find the now-ubiquitous power supply on/off switch and a three-prong plug for peripheral devices. As someone with far too many power bars and surge suppressors filled to capacity, the extra plug is something I can really appreciate. No, you won’t be able to plug in large, boxy power adapters because of the way the plug is oriented, but any normal-sized plug will fit and not get in the way.
Peripheral devices are moving towards pulling power directly from your PC via, for example, your USB ports, so the need to plug in a huge number of peripherals is diminishing, somewhat. However, it will likely be quite some time before monitors start pulling juice from system ports, so the Stealth 520W’s extra plug will certainly come in handy there. Heck, with graphics cards like ATI’s Radeon 9700 Pro requiring extra internal power connections, there’s no telling what kinds of power and plug requirements we’ll see from future products.
None of the other power supplies in this comparison feature the extra rear panel plug, and Vantec also provides a few extra connectors on the inside.
Vantec serves up 10 full MOLEX connectors on the Stealth 520W and throws in the standard two FDD power plugs for good measure. If you’re using a power supply this stacked, I’d wager you’re far more likely to be plugging a graphics card into one of those FDD power connectors than a dated floppy drive. Users with full tower cases rejoice; the Stealth 520W’s longest MOLEX connector will reach a full 42″, which should be enough to hit even hard drives buried on the bottom of massive cases.
With an eye towards broader compatibility with different motherboards, the Stealth 520W actually features a 24-pin rather than 20-pin motherboard connector. Vantec ships a 24-to-20 pin adapter in the box, which means that the Stealth 520W retains compatibility with virtually any available motherboard. However, Tyan’s S2466, S2462 dual-Athlon server boards, and S2603 i860 boards are not compatible with the power connector, which is disappointing. I don’t mind high-end server boards like the MPX and i860-based Thunder series being unsupported, since that class of motherboard definitely has special needs given integrated features like on-board SCSI, but it really hurts that Vantec doesn’t officially support the Tiger MPX, which is a solid platform for SMP enthusiasts.
The 24-pin adapter is able to give the Stealth 520W’s motherboard power cord a little extra reach, and you can plug in a motherboard a full 30 inches away from the PSU itself. To foil that kind of reach, motherboard manufacturers are going to have to really mess up power plug positioning.
Like Antec, Vantec wraps its motherboard power cord in a plastic sheath, this time zip-tied at each end. The zip ties aren’t quite as slick as Antec’s heat shrink wrapping, but they do the trick.
We generally classify power supplies by their total output wattage, but sometimes there’s a little more going on with output wattages under the hood that requires a closer look.
|Maximum output (W)|
|Antec TruePower 380W||92.4||175||216||360|
|Antec TruePower 550W||105.6||200||288||530|
|Thermaltake Purepower 360W||220||204||360|
|Vantec Stealth 520W||260||336||520|
As you can see, the Thermaltake and Vantec power supplies share wattage between the 3.3 and 5V lines. Antec, however, isn’t limited because it has dedicated output circuitry for each voltage line. So, while the other power supplies in this comparison have to share wattage between the 3.3 and 5V lines, Antec’s TruePower power supplies are deliver set, unshared wattages on each line.
With a balanced load spread over all three voltage lines, none of the power supplies should have problems. However, Antec’s TruePower units have an edge with devices on the 3.3 and 5V lines because the lines don’t share power. You can load up with 3.3V devices and not have to worry about cannibalizing wattage from the 5V line, and vice versa.
Since we’ve covered voltage, we might as well go over current output with a fancy little chart.
|Maximum output current (A)|
|Antec TruePower 380W||28||35||18||0.5||1.0||2.0|
|Antec TruePower 550W||32||40||24||0.5||1.0||2.0|
|Thermaltake Purepower 360W||28||35||17||0.3||0.8||2.0|
|Vantec Stealth 520W||26||52||28||1.0||0.8||2.5|
The highs and lows are spread all over the maximum current output chart, with each manufacturer favoring a different voltage line. And, of course, the lower the wattage, the lower the output currents are going to be.
Our testing methods
To test the power supplies, I packed a system to the gills with all sorts of extra hardware, even an old Voodoo2 12MB. The test system was filled to simulate extreme loads and push the power supplies to their limits. Sure we could have run a low-end system with only a couple of PCI cards and a single hard drive and optical drive, but I’m not sure anyone is looking at 550W power supplies for that kind of setup.
Albatron KX400+ Pro
AMD Athlon XP 2100+
768MB (3 DIMMs)
CAS 2.5 PC2700 DDR SDRAM
GeForce4 Ti 4600
Hercules Muse LT
D-Link 10/100MBit NIC (two cards)
3ware Escalade 7500-4
IBM 60GXP 40GB 7200RPM ATA/100 hard drive
Windows XP Professional
We used the following versions of our test applications:
Testing power supply performance is quite a bit different than what you’re used to seeing with video cards, processors, or chipsets. There are two relatively simple tests, whose methods you can find described in the next section. The above test applications were used to stress test the system while we measured voltages and noise levels.
The test systems’ Windows desktop was set at 1024×768 in 32-bit color at a 75Hz screen refresh rate. Vertical refresh sync (vsync) was disabled for all tests. Most of the 3D gaming tests used the high detail image quality settings in 32-bit color.
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.
Power supplies should provide consistent, accurate voltage on their 3.3, 5, and 12 volt lines. If voltages are way off or fluctuate wildly, system components could be damaged. So, to find out exactly what each power supply puts out on the 3.3, 5, and 12 volt rails, we broke out a digital multi-meter and did some testing.
All of the power supplies exhibited stable, fluctuation-free voltages at idle and under load, but there was some slight variation in what voltages each unit actually supplied. Let’s see how each power supply did in our tests.
Both Antec and Vantec’s power supplies deliver close, consistent voltages over the 3.3V rail. Thermaltake’s Purepower 360W is out by 3.5% at idle and while under load, which is actually inside Thermaltake’s advertised tolerance for 3.3V output.
On the 5V rail, things are pretty tight. Only the Thermaltake and Vantec power supplies falter, ever so slightly, under load, but they’re both running acceptably close to the 5V target. The Vantec Stealth 520W is running a little low at idle and under load, but it’s well within its 5% tolerance.
Both Antec power supplies come in a little low on the 12V rail, but only by 1.1%, which is well within Antec’s 3% tolerance here. The Vantec and Thermaltake power supplies are actually farther from 12V than Antec’s, but both are within their manufacturers’ 5% output tolerances.
Just for fun, I threw an old, generic, 300W power supply into the test system just to see how it would run. Well, it didn’t. That generic 300W power supply has run low-end systems with fairly sparse hardware specs quite well in the past, and it will probably run low-end systems without fail in the future, but the purpose of our stress testing was to reveal weakness under extreme loads, not light ones.
The power supplies we’re testing today have a lot of diversity when it comes to the number of fans. Vantec’s Stealth has three fans and a variable fan speed switch. Antec packs two fans on their 550 and 380W power supplies, and Thermaltake keeps things cool with only a single fan and a whole lot of venting.
To test noise levels, we fired up our test system and placed a decibel meter three inches from each power supply’s rear fan. We ran the system at idle and under load, and you’ll find the results below. Since the Vantec Stealth 520W has three different fan speed settings, you’ll find scores for each speed setting.
Even with the slowest fan speed setting, Vantec’s Stealth 520W is noticeably louder than the rest of the field. It might not be quite as loud as the Stealth bomber, but it’s up there. Despite having two fans, Antec’s TruePower models are barely louder than the single-fan Thermaltake Purepower 360W at idle, and they actually produce less noise under load. However, the noise levels under load between the Antecs and the Thermaltake are really quite close overall.
This power supply review over at Lost Circuits inspired me to take my testing one step further and perform a short-out crash test to verify the safety features of each power supply. The test involves shorting out the 12V line to ground while the system is under full load, which means it’s not exactly for the faint of heart. I don’t recommend performing this test yourself, since you risk, at worst, frying your system’s components and possibly causing harm to yourself in the process. I repeat: do not try this at home, The Tech Report isn’t liable for any harm to you or your system just because you wanted to see a few sparks.
I set out to cobble together an expendable test system for crash testingsomething I could afford to lose, just in case. Thank god for Socket 423 Pentium 4 processors and RDRAM!
With each unit, I loaded up the system and shorted out the 12V line. Pop. After a few minutes, each of the power supplies booted up and ran as if nothing had happened at all. Just to be sure everything was in working order, I tested the voltages again to make sure there were no wild fluctuations, and there weren’t. Each power supply survived with nothing more than a few sparks to show for it.
We really weren’t able to do any long-term testing on the power supplies, since long term in this case should really mean years rather than months or weeks. However, we did beat on the power supplies as much as we could to try and bring them to their knees. It’s not a substitute for real long-term testing, but by the time we’d be done with that, you might not even be able to purchase the power supplies in question.
We’ll continue abusing each of the power supplies and post an update if we encounter any problems down the road.
All in all, I was quite impressed with all the power supplies in this comparison. They each offer something unique, and which one is right for you largely depends on your needs. For the purposes of my following recommendations, I’m only going to consider the power supplies I’ve actually tested, but keep in mind that each manufacturer offers a wider range of wattages for each power supply model, and the pricing for each is different. If you’re short on cash, Thermaltake’s Purepower 360W is the cheapest of the bunch. Even with its seemingly meager 360W power rating, it was still able to handle our stress testing without complaint. A single fan makes the Purepower 360W the quietest power supply in the comparison, at least under load, so it’s not a bad buy for $58.
Only 360W of power might seem pokey to some of you, and if you’re running an overclocked multi-processor rig with SCSI or RAID and a bunch of drives, the Vantec Stealth 520W should keep your devices fed with ample amounts of juice. If you’re running a hot system, the three fans should keep internal case temperatures lower than a dual or single-fan power supply, but you’re going to pay a high price in noise, even with the slowest fan speed setting. Still, the Stealth is as close as a power supply is going to get to having style, and it does boast the highest number of power connectors and the longest cable lengths. Sex appeal doesn’t come cheap, though. The suggested retail price for the Stealth 520W, which has yet to hit the online marketplace, is $149US.
Antec’s exterior may be boring, but there’s a lot of cool stuff going on under the hood, and even the 550W power supply is nice and quiet. Both Antec models are also quite reasonably priced; the 380W model is available for $70US, while its 550W big brother can be had for only $100. That’s a pretty sweet deal for power supplies with dedicated output circuitry, tight tolerances, and impressively low noise levels under load.
I’m happy to make both the Antec TruePower power supplies we tested today our Editor’s Choice. Pick whichever suits your wattage needs, and you won’t be disappointed. The low-wattage end of the TruePower line is perfect for anyone looking to power a low to mid-range system that might have otherwise been subjected to a generic power supply. The high-wattage end of the line should be enough to keep all but the most image-conscious enthusiasts powered, stable, and happy.