Thoughts and Recommendations

So there you have it, another 12 power supplies reviewed and dissected. This time, our conclusion is a little easier because there are only a few models that really stuck out from the crowd. There are a few areas where companies try to differentiate, and which areas you think are most important will influence our recommendation.

First we have acoustic noise, which can be critical if you want to build a "silent" computer. Next we have efficiency, which is often overhyped considering a 1% or even 2% difference doesn't really equal a lot of money over the course of the year. Still, all things being equal, higher efficiency is desirable. Cooling performance is also important, and is often directly related to the efficiency -- although the components also play a large role. Some are also interested in the features of the power supply (i.e. cable lengths, cable management, accessories, etc.) Finally, we have voltage stability and quality, which is arguably the most important aspect -- especially if you plan on overclocking your system.

Below we've listed the various areas you might focus on, along with PSU recommendations that do particularly well in that category.

Cable Lengths and Connectors

There were a lot of differences between most of the power supplies, as we've already discussed. The Arctic Cooling PSU is the only unit that doesn't include an 8-pin ATX connector. We talked with the company about this, and they insisted 8-pin connectors aren't necessary -- you can just use a 4-pin connector in half of an 8-pin jack on your motherboard. While it may work, we would still prefer to have an 8-pin connector; if it's unnecessary, why do motherboards have eight pin jacks?

The ATX cable lengths on the Arctic Cooling Fusion, Akasa Green Power, BFG LS-550, and OCZ ModXStream Pro are rather short at just 40 cm, which would definitely be a problem in larger cases or bottom mounted PSU designs. The Tagan SuperRock has the longest ATX cables at 55 cm. The remaining power supplies are 50 cm, which is the "standard" length.

The good news is that all of the tested power supplies have at least two PEG connectors, which is enough to run either a lower-end SLI/CF setup or a single high-end graphics cards with two PEG jacks. Arctic Cooling is the only unit that provides four PCI-E connectors. Cable lengths are also quite different; if you need longer cables, we recommend the Tagan SuperRock, Seasonic S12II or M12II, or the BFG LS-550.

We already discussed the relative importance of SATA and Molex connectors. A typical PC might only need one of each, and even high-end PCs might only need four or five of each connector type. We wanted to fully populate the drive bays in computer cases that we test, so we had PC Power & Cooling build us a custom Turbo Cool 860 with 15 SATA connectors, but most people don't need that kind of setup. If you do want more connectors, out of the tested power supplies we recommend the Tagan units. Both include eight SATA connectors and six Molex connectors, with very good cable lengths. Arctic Cooling provide six SATA connectors, but they are on a single harness which could prove problematic in certain cases.

DC Voltage Regulation and Quality

All of the power supplies stayed within specifications, which is very good to see. Since these are mostly high-end units, we didn't expect anything less, but kudos regardless. Many of the power supplies stayed within 3% regulation, which is what most companies aim for. Ideally, voltages should start about 1% above the nominal value and stay in that range. Most 3.3V and 5V rails ended up dropping about 3% below regulation, but ripple and noise was generally good.

A few of the units come pretty close to the maximum and minimum allowed voltages on the various rails, for example the Sunbeam. Ripple also exceeded specifications by a few millivolts on the Sunbeam. Overall, the 12V rail is the most important rail, and the BFG LS-550 manages an impressive 1.5% regulation on this rail. Seasonic also scores some points here with the tightest regulation we have seen to date.

Efficiency

A quick look at the efficiency chart shows there's only one power supply that provides superior efficiency at all voltage inputs, and that's the BFG LS-550. With 120VAC it starts at 82% efficiency and reaches a maximum of 86% efficiency; 230VAC performed even better, with 86% efficiency at 20/80 loads and a maximum of 88% efficiency at 50% load. The Arctic Cooling Fusion also performs well, reaching 88% efficiency at a medium load. The Cooler Master Silent Pro does well on 230VAC, but it has minor flaws on 120VAC.

All of the other units manage to reach 85% efficiency (230VAC), which is pretty typical these days. Considering the performance of the BFG, which is manufactured by Enhance, we expected similar performance from Tagan; unfortunately, that's not the case. We would like to see Tagan work on refining their unit to match the performance of BFG.

Acoustic Noise

Acoustic noise is often an important consideration, and many people want their computers to be seen and not heard. Our equipment can measure down to 17 dB(A), at which point background noise comes into play. Noise levels at medium load and lower are typically the important consideration, since few users actually run their power supplies at more than 50% load. Our charts show that most of the power supplies are able to remain very quiet below 50% load, to the point where other components in the computer will almost certainly generate more noise.

The Arctic Cooling Fusion again warrants a mention, with 17 to 18 dB up to 50% load. The Cooler Master Silent Pro performs superbly, along with the Tagan SuperRock, and both remain below 20 dB. Akasa, Corsair, and Enermax also perform well. Seasonic and Sunbeam prefer to take the safe route and spin the fans faster in order to keep temperatures down, which is often the better course of action if you prefer longevity overload noise.

Cooling Performance

Not surprisingly, the crown for the best cooling performance goes to Seasonic. This goes hand-in-hand with their higher noise levels, which helps to keep temperatures in check. Seasonic also built the Arctic Cooling Fusion, which delivers very good results. Our temperature chart looked at Delta K, the difference between internal and exhaust temperatures. The only three power supplies to generate negative scores are built by Seasonic. Akasa, BFG, and Corsair don't quite match the Seasonic built units, but performance is very good in all three cases.

Unfortunately, the Sunbeam Tuniq Prophecy didn't survive our burn-in test. It self-destructed under full load at 40°C, so we definitely wouldn't recommend that power supply unless you live in a cold environment or only plan to run at lower loads. All of the other units survived heat conditions of 50°C.

Prices

Last, we come to prices, which for some people is far and away most important factor in choosing a power supply. Not all of the units are available in all locations, so you will also have to take that into consideration. The BFG LS-550 is only available in the US right now, but we've seen other BFG power supplies in Europe so we have high hopes it will soon be there as well. For the overall performance it delivers, the BFG is an excellent bargain at $70. The Arctic Cooling Fusion is available for €55 or $64, and at that price it's a great bargain. The Tagan SuperRock also perform very good, and a price of €64 makes it our third choice for overall value and performance.

On the opposite end of the scale, the Enermax Liberty Eco is simply too expensive right now. The Cooler Master Silent Pro could also do with a slight price drop. Seasonic makes good power supplies, but they also make power supplies for a lot of competitors. As such, they tend to charge more for their own brand in order to avoid competing with their clients on similar products.

Comparison: Prices Awards
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  • Christoph Katzer - Friday, February 20, 2009 - link

    You can find the review here
    http://www.anandtech.com/casecoolingpsus/showdoc.a...">http://www.anandtech.com/casecoolingpsus/showdoc.a...

    There are tons of others in the Cases/Cooling/PSUs section you might want to check out.
  • Nickel020 - Saturday, February 21, 2009 - link

    There are reviews there, but it would be good if you could include PSUs you already reviewed in the conclusion to say how they measure up to the currently reviewed units.
    Most people just don't know enough about PSUs to judge how good that PSU in the single review is compared to the ones in the round-up.
  • kilkennycat - Friday, February 20, 2009 - link

    No details on whether the SATA power connectors are right-angle or straight. For each power supply it would be very useful to detail the distribution of right-angle vs straight.. even to the extent of picturing or sketching the cables. In many of the mid-sized or uATX cases in which these power supplies might be used, the hard-disks may overhang the motherboard components or might bump into the rear of a video card. Remember that the SATA hard-disk power-port is much closer to the motherboard and its mounted components than the 4-pin Molex on PATA units. A right-angle SATA power connector might make all the difference between a comfortable fit and having to purchase a 4-pin Molex to right-angle SATA power adapter. I have run into this problem several times with computer cases where the hard-disks are mounted cross-wise and with little clearance between the rear of the hard-disk and the side-cover. Also my latest experience of this problem was on a recent uATX build that required 3-disk storage. The clearance space between one of the hard-disks and the motherboard memory DIMMS required a right-angle SATA power-connector. I had to satisfy that requirement with a 4-pin Molex to right-angle SATA power adapter.... If I had known in advance how many right-angle SATA power connectors came with the power-supply, I could have ordered the adapter in advance.....
  • Christoph Katzer - Friday, February 20, 2009 - link

    Quickly done, Akasa has the only angled SATA connectors and I Don't see that too often either...
  • kilkennycat - Sunday, February 22, 2009 - link

    Thanks for the reply.

    The Corsair HX520W Modular Power Supply has 2 modular SATA cables, each with one right-angle and one straight connector - a reasonable compromise.

    Btw, the fact the Corsair HX520W was entirely missed from your 500-550W roundup is rather odd, with its high quality (HardOCP Review Gold Star, Dec 2007), 2-year-production quality history (now up to over 400 customer reviews on Newegg - 5 stars, uniquely unusual for a power-supply) It also has triple 18A max 12V outputs --- unlike those less expensive to manufacture with only one 12V rail and umpteem amps on that rail. The single-12V high-wattage power-supplies totally ignore Intel's SAFETY recommendation of a maximum of 20A per 12V output. An internal quasi-short - dendrite growth, fine metallic bits, loose wire-clippings etc - involving the 12V rail and with one of these 40-50amp 12V current power-supplies can potentially turn your PC instantly into a very handy radiant heater/fire-source.
  • strikeback03 - Monday, February 23, 2009 - link

    Are you talking about this roundup? The Corsair is in there.
  • kilkennycat - Tuesday, February 24, 2009 - link

    Oops !!! MANY APOLOGIES to both you and Christopher. I was speed-reading the Introductory page and read the following :- "We have four units manufactured by Enhance, four more from Seasonic, two by Sirtec, one Enermax, and one Topower. " I did not realize that Christopher was referring there to the original power-supply OEMs and not the retail labels. It would have been nice to have a list of the actual retail model numbers of the 12 power-supplies on the intro page. As it was, I only read the first few reviews and quit before I got down as far as the Corsair..... Again, many apologies. Long day, late night reading, insufficient reading stamina....
  • Nickel020 - Friday, February 20, 2009 - link

    First off, great job on the performance review part! The graphs are great and much easier to understand than the usual screenshots from the measuring software.
    I'm a little disappointed by the acoustics part though. dB measuremeents are pretty much useless since they don't really reflect subjective sound perception. PSUs with "more" dBs will often be considered quieter, in fact, dB measurements don't reflect the ranking of PSUs that you will find on silentpcreview.com
    Measurements in Sone would be much better, but I guess the testing equipment is somewhat expensive :(
    Since you're also from Germany, wouldn't some kind of cooperation with PCGH or even c't be possible?
    Something else that I'm missing here is a Be Quiet! unit, but I think they're pretty similar to the Tagans, are they not?

    That's all :)

    Thanks again for the article!
  • Nickel020 - Saturday, February 21, 2009 - link

    One more comment:
    What happened to the fan speed/load curves?

    Those were really useful fo judging acoustics. If you know the fan that was used in there then you can judge the subjective noise at a certain RPM pretty well.
  • philosofool - Friday, February 20, 2009 - link

    I bookmarked this article because I want to have it around next time I'm shopping for computer parts. Unlike processors and similar components, where every extra dollar spent usually comes with a little more perforamnce, PSUs are an area where price and quality come apart. I want a stable, cool, QUIET PSU, and I want to pay as little as possible to have that. Every dollar I save getting a PSU that will do just what I need is another dollar I can spend on a video card. This article is going to help me build a better machine.

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