Corsair HX650w 650W ATX PSU

Simulated Load Testing

Corsair HX650w

To provide accurate and consistent results in all of our PSU testing, Overclock3D uses professional grade DC electronic load equipment capable of placing a sustained load of 3690w across a total of six rails (including +5vsb and -12v) on the PSU!

This is achieved by using a combination of SunMoon and Analogic electronic load equipment which allow us to adjust amperage loads in increments as small as 0.01A while also measuring voltage and wattage readings on-screen.

During today's tests, we will be placing the Corsair HX650w under 25%, 50%, 75% and 100% load levels inside a hot box regulated to a temperature of around 50°C. Additional 'Cross Load' and a 'Max Load' tests will also be performed under these conditions to simulate how the PSU reacts to heavily uneven loads as well as running above its specified output.   

Corsair HX650w Results @ 50°C
   +3.3v  +5.0v  +12v  +5vSB  -12v  AC Watts /
 DC Watts
 Efficiency  Intake /
Δ Temp
Test 1
5.25A 5.25A 9.50A  0.75A  0.20A 190w /
 86.84% 50.4°C /
3.37v 5.08v 12.10v 5.01v  -11.94v
Test 2
10.50A 10.50A 19.00A 1.50A  0.40A  377w /
 87.26%  50.3°C /
3.34v 5.04v 12.06v 4.97v  -11.95v
Test 3
15.75A 15.75A 28.50A 2.25A  0.60A  567w /
 86.59% 50.2C /
3.30v 5.00v 12.02v 4.93v -12.00v
Test 4
21.00A 21.00A 38.00A 3.00A 0.80A 771w /
84.43%  50.6°C /
3.26v 4.95v 11.96v 4.89v -12.04v
Test 5
21.00A 21.00A 1.00A 0.00A 0.00A 240w /
75.00% 50.8°C /
4.0 °C
3.27v 4.77v 12.12v 5.01v -12.13v
Test 6
 1.00A  1.00A  57.00A  0.00A  0.00A 716w /
87.98%  51.0°C /
3.38v 5.07v 11.96v 5.00v -12.68v
Test 7
 21.00A 21.00A 44.00A  3.00A  0.80A 858w /
84.14%  51.2°C /
3.25v 4.94v 11.96v 4.89v -12.10v
Corsair HX650w Performance Overview
 +3.3v Diff.
 +5.0v Diff.
 +12v Diff.
Avg Effic.
Noise Rating
-3.26%   -2.55% -1.15%  86.28% Low 

Looking first at the performance overview chart directly above, we can see that the HX650w manages an average efficiency of 86% in the standard tests 1-4. This is pretty much in line with Corsair's advertised efficiency of 85% given a small margin of error on our part and Corsair's tendency to under-hype their PSU specs. Of course, this is also the first place where we can truly see a difference between the HX650w and the HX620w, with the latter 'only' achieving ~80% efficiency, which to be fair, was good for its day. Voltage stability is also very reasonable on all of the main rails, with the highest fluctuation of 3.26% being well within acceptable tolerances.

Moving on to the first cross-load scenario in test 5 shows that the HX650w isn't too keen on running without a load on its +12v rail. However, as I've said before, this particular test isn't something likely to be reproduced in a real world scenario (who would buy a 650w PSU to only run it at 180w load on the +3v/+5v rails?). So really the results here are somewhat forgivable. Cross-load test 6 on the other hand needs no forgiveness at all, with the HX650w delivering near on it's full output on the +12v rail alone, and with efficiency results approaching almost 88%!

The final test, is of course the one that every PSU manufacturer fears the most....MAX Load. In this test the PSU is pushed as far as it can go before it either engages its safety features, or spits more flames out of its exhaust grill than the Batmobile. Recently I've had quite a few of the latter, but thankfully the HX650w didn't follow suit and managed to deliver a respectable and sustainable 722w. Attempting to go any higher simply resulted in the PSU shutting down safely. Phew.

Corsair HX650w Scope Results @ 50c
   +3.3v  +5.0v  +12v
Test 1
Test 2
Test 3
Test 4
Test 5
Test 6
Test 7 (MAX)

Ripple refers to the small fluctuations in voltage that occur in all PSU's on a millisecond scale. Large quantities of ripple on a PSU can damage or kill components in your PC over time and therefore testing a PSU's performance in this area is just as important as any other part. Unfortunately ripple cannot be measured using a standard multimeter and requires a specialist device called an oscilloscope. The results you see above are taken from our Rigol 25Mhz 400MSa/s scope that can save 'screenshots' of its data to a USB memory stick.

ATX specification states that ripple should be no higher than 50mV on the +3.3v/+5v rails and 120mV on the +12v rails, and judging by those flat lines in the screenshots above, the HX650W certainly had no trouble at all meeting these requirements throughout almost all of the tests. Only in the cross-load test 5 does the ripple on the +5v rail hit 70mV, but once again we need to remember that this particular load scenario is highly unlikely to ever be encountered in the real world. The rest of the results on the other hand are exceptional with the +3.3v and +5v rails rarely budging from around 10mV and the +12v rail only hitting 42mV in test 6 when the PSU is already running 70w higher than its rated output. Absolutely awesome work Corsair!

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Most Recent Comments

15-01-2010, 03:05:32

The banners are out, the drinks are flowing... Whats the occasion? Jimbo is finally back in the reviewers chair and is taking a look at the Corsair HX650W power supply.

Continue ReadingQuote

15-01-2010, 03:57:33

Great review Jim, your test area must look like a NASA lab room :P Great to see you back mind ;-)Quote

15-01-2010, 04:42:40

Cheers mate. And yea, when people come round they do give me a bit of a strange "are you a terrorist or something" look Quote

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