Comparison: DC Output Stability

Stable voltage output is what power supplies are designed to provide. They need to deliver the proper voltage to components so that they can function correctly. The higher the load gets, the more difficult it is for a power supply to deliver the desired voltage; this results in a constant voltage drop with increasing current. With the following graphs, we want to show the stability of these rails during operation. We show the range in which a power supply is able to provide the correct voltage. For these charts, we take the average deviation of all the measured results. The lower results indicate better compliance to regulations - i.e. less over- or undervolting on the rails - which means the PSU is better.


DC-Output
Stability 3.3V Rail


DC-Output
Stability 5V Rail


DC-Output
Stability 12V Rail

The unit from Hiper shows very good results, taking first place on the lower voltage rails. The deviation here is about 3%, which is very good and stable score. The other units aren't much worse, but they're still not as close to spec as the Hiper unit. With the 12V rails, things are slightly different. Here we have three power supplies rising above the rest. The units from be quiet!, Thermaltake, and Hiper are all within 1.57% of spec. In general, the regulation on the 12V rails runs much tighter with all of the units.

Comparison: Cable Length Comparison: Efficiency and Acoustics
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  • larson0699 - Monday, August 4, 2008 - link

    You mentioned that the label on the Thermaltake unit doesn't state maximum combined load of the lower-volt rails.

    But look, it does. 180 Watts.
  • BRDiger - Tuesday, July 29, 2008 - link

    I kind a wondering because comparing the efficiency level of the Be Quiet! to the testing datasheet on the 80plus.org site it just reaches about 80% at 100% load unlike your results with nearly 84%. Comparing it to the Enermax Modu 82+ review here, it even exeeds its efficiency
    Just wondering and it´s not supposed to be an offence...
  • BRDiger - Tuesday, July 29, 2008 - link

    Well, after reading another review it seems that 80plus was actually wrong and the be quiet!s performance exeeds the enermax..
  • strikeback03 - Friday, February 22, 2008 - link

    Thermal and fluids was not my best subject in school, but don't fans usually lose air off the tips of the blades, not suck it in? That is my experience with the Zerotherm Nirvana, which seems to make the same claim of sucking air in with its open fan.
  • mo3 - Friday, February 22, 2008 - link

    The new Enermax Modular 82+ & Pro 82+ can peak over 700Watts with out a problem; also they have the ATX12v V2.3 and reaching 88% efficiency.
    Modular 82+ has 2x 12 pin connection embedded for up and coming graphics cards and greater stability.

    Just to give the readers a better alternative! :)

    Check out more info at: www.enermax.co.uk
  • crimson117 - Friday, February 22, 2008 - link

    Okay... PSU review.. new 9600 GT review... I think anandtech is trying to tell me I need a new computer!
  • NINaudio - Thursday, February 21, 2008 - link

    Hi, you mention that the be quiet! PSU is quiet but also runs warmer than the others. Where are the temperature charts that we've seen in previous PSU reviews? It would be good to see the temperatures that you sacrifice for a quieter PSU. Is it a degree, 5 degrees, ten degrees, more?
  • tynopik - Thursday, February 21, 2008 - link

    1. include a real stress test like how the units handle rapidly changing input voltage

    say load them up to 80% capacity and then connect them to a variac and dip the voltage to ~90V 3 times in quick succession to simulate a brownout or poor electrical conditions and check that
    a) it doesn't blow up
    b) it maintains quality output while the input if fluctuating

    2. include cheapo units for comparision just for the reminder of what a poor quality unit is

    3. i really love your connector length charts, far more useful than the usual 'stetch a jumble of cables out and lay a ruler next to it' approach. i just wish you would do the same for the sata/peripheral connectors

    4. i'm really like the way you combined all the acoustic and efficiency charts together instead of having a bunch of individual charts
  • Christoph Katzer - Thursday, February 21, 2008 - link

    I just assembled a nice system do to those tests. Once it's up and running I will include it. Will also make a comparison of all cables from now on, thanks.

    The problem with cheap units is that they are mostly for a specific market. I would need to buy thise units myself since no company would ever send them over. Since I am not in the US I will only have the stuff from Europe which is not even available in the US. But let us see how we could change that in the future...
  • jtleon - Thursday, February 21, 2008 - link

    Chris,

    You state that at least 100W must be drawn before these units achieve high efficiency. Can you relate this requirement to most normal PC tasks - i.e. browsing the web (reading Anandtech reports of course), answering email, other office based activities (the majority of PC users on the planet), rather than those hardcore gamers that are gaming around the clock (and clearly are independently wealthy!).

    It would appear that these PSU's are not going to efficiently reduce the carbon footprint of the majority of PC users on this planet.

    Am I wrong?

    Regards,
    jtleon

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