Corsair HX750w (750w) ATX PSU

Simulated Load Testing

Simulated Load Testing
 
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 HX750W under 25%, 50%, 75% and 100% load levels at both room temperature and 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 HX750W Results @ Room Temperature
   +3.3v  +5.0v  +12v  +5vSB  -12v  AC Watts /
 DC Watts
 Efficiency  Intake /
 Exhaust
Δ Temp
Test 1
(Low)
4.37A 4.37A 12.00A  0.75A  0.20A  206w /
188w
 91.26% 28.6°C /
39.3°C
10.7°C
3.32v 5.09v 12.16v 5.06v  -11.83v
Test 2
(Med)
8.75A 8.75A 24.00A 1.5A  0.40A  404w /
376w
 93.06%  29.0°C /
45.0°C
16.0°C
3.30v
5.07v
12.12v 5.02v  -11.75v
Test 3
(High)
13.12A 13.12A 36.00A  2.25A  0.60A  608w /
563w
 92.59%  29.3C /
48.5°C
19.3°C
3.27v 5.05v 12.10v 4.98v -11.73v
Test 4
(Full)
17.50A 17.50A 48.00A 3.00A  0.80A 820w /
748w
91.21%  29.5°C /
51.8°C
 22.3°C
3.24v 5.03v 12.08v 4.93v -11.72v
Test 5
(x-load)
17.00A 18.00A 1.00A 0.00A 0.00A  189w /
159w
84.12% 29.1°C /
35.9°C
6.8 °C
3.29v 5.07v 12.16v 5.11v -12.46v
Test 6
(x-load)
 1.00A  1.00A  61.35A  0.00A  0.00A  808w /
750w
92.82%  29.9°C /
50.4°C
 20.5°C
3.29v 5.06v 12.10v 5.06v -13.14v
Test 7
(MAX)
 21.00A  21.00A 59.00A  4.00A  0.80A  1013w /
913w
90.12%  29.9°C /
54.5°C
 24.6°C
3.22v 5.01v 12.06v 4.87v -11.78v
 
Comparing the results in tests 1-4 with those of the HX850w, there really is very little difference between the two units. The voltages show roughly the same amount of droop from 25% (Low) to 100% (Full) load and efficiency is highest in tests 2 and 3 at around 93%, while tests 1 and 4 also do extremely well at around 91% efficiency. Intake and exhaust temperatures are the only areas which show significant difference to that of the HX850w, but this is more than likely down to our recent upgrade to a Fluke 52-II digital thermometer which is hooked up to two 'K' type thermal probes for more accurate delta temperature readings.
 
Cross-load tests 5 & 6 tell a very similar story to that of the HX850w, with the voltages and efficiency levels once again being pretty much a mirror image. The lowest efficiency level is seen in test 5 with the unit dropping down to 84.12%, but the scenario of a PC system using over 170w on the +3.3v and +5v rails and only 12w on the +12v rail isn't something that you're ever likely to come across in the real world.
 
Finally in test 7 the HX750w was pushed as far as it could go without OCP (Over Current Protection) kicking in and switching the unit off. This is the one test that could actually tell us if the HX750w is simply a re-badged HX850w, or if indeed there are some minor differences inside the unit that give it its 100w lower power output. With a whopping 21A load on both the +3.3v and +5v rails and 59A on the +12v rail, the HX750w topped out at a total of 913w. This is of course WELL above its rated output, but still a little below that of the HX850w which managed an amazing 1084w before showing signs of weakness. However, even at these extremely high loads, the HX750w managed 90.12% efficiency along with some rock solid voltage outputs.
 
Corsair HX750W Results @ 50c
   +3.3v  +5.0v  +12v  +5vSB  -12v  AC Watts /
 DC Watts
 Efficiency  Intake /
 Exhaust
Δ Temp
Test 1
(Low)
4.37A 4.37A 12.00A  0.75A  0.20A  206w /
188w
 91.26% 52.9°C /
55.3°C
2.4°C
3.33v 5.09v 12.14v 5.06v  -11.87v
Test 2
(Med)
8.75A 8.75A 24.00A 1.5A  0.40A  406w /
376w
 92.61%  52.6°C /
58.7°C
6.1°C
3.30v
5.07v
12.12v 5.02v  -11.79v
Test 3
(High)
13.12A 13.12A 36.00A  2.25A  0.60A  611w /
563w
 92.14%  53.1C /
61.6°C
8.5°C
3.27v 5.05v 12.10v 4.97v -11.78v
Test 4
(Full)
17.50A 17.50A 48.00A 3.00A  0.80A 824w /
747w
90.65%  52.4°C /
64.8°C
 12.4°C
3.24v 5.03v 12.06v 4.92v -11.79v
Test 5
(x-load)
17.00A 18.00A 1.00A 0.00A 0.00A  189w /
159w
84.12% 51.0°C /
55.0°C
4.0°C
3.29v 5.07v 12.14v 5.11v -12.46v
Test 6
(x-load)
 1.00A  1.00A  61.35A  0.00A  0.00A  815w /
749w
91.90%  51.6°C /
60.8°C
 9.2°C
3.29v 5.06v 12.08v 5.06v -13.14v
Test 7
(MAX)
 21.00A  21.00A 59.00A  4.00A  0.80A  1002w /
887w
88.52%  54.3°C /
66.0°C
 11.7°C
3.21v 5.00v 12.04v 4.86v -11.85v
 
Bumping up the ambient temperature to a toasty 50°C and re-running the room temperature results, hardy anything at all changed. In fact, aside from the odd +/-0.2v fluctuation on a couple of the rails and a few dips in efficiency, the only real thing worth talking about is the MAX load test which topped out at 887w - 26w lower than in the room temperature tests. This is by no means anything to get upset about as the HX750w is still operating at 137w above its rated capacity, and with 88% efficiency too.
 
Corsair HX750W Scope Results @ 50c
   +3.3v  +5.0v  +12v
Test 1
(Low)
T1_3.3V T1_5V T1_12V
Test 2
(Med)
t2_3.3v t2_5v t2_12v
Test 3
(High)
t3_3.3v t3_5v t3_12v
Test 4
(Full)
t4_3v t4_5v t4_12v
Test 5
(x-load)
t5_3.3v t5_5v t5_12v
Test 6
(x-load)
t6_3.3v t6_5v t6_12v
Test 7
(MAX)
T7_3.3 T7_5 T7_12

Finishing up the testing, snapshots of the HX750w's +3.3, +5 and +12v rails were taken using a Rigol 25Mhz 400MSa/s oscilloscope while installed inside the 50°C hot box. Unfortunately there's not enough room on the page to put these side-by-side with the results from the HX850w, but if you're interested, the 850's results can be found here.
 
Once again the HX750w closely resembles that of the HX850w giving stunning results with the +3.3v and +5v rails staying at or below 10mV ripple in tests 1-6 and only hitting 12mV ripple in test 7 on the +5v rail. The +12v rail was also extremely clean with ripple starting at 12mV in test 1 and only increasing to 40mV by test 4. Test 7 saw the ripple hit 52mV, which is 10mV higher than that of the HX850w, but still way below the maximum of 120mV as specified by ATX standards.
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Most Recent Comments

27-08-2009, 16:06:57

Rastalovich
Corsair have definitely moved up to one of 'the' psus I look for when pondering a shopping cart. Having also had a few questionable situations with psus other people had praised for years.

Great stuff, just like the 850.Quote

27-08-2009, 16:56:18

Hope
I am convinced, will be investing very soon

Thanks for such a good review Quote

27-08-2009, 17:43:15

tinytomlogan
Quote:
Originally Posted by name='Hope'
I am convinced, will be investing very soon

Thanks for such a good review
*cough cough* Told ya Quote

29-08-2009, 08:16:42

Kylevdm
I have just installed on of these in my PC although, I almost died at the smell of new plastic from the bags when I opened it, at least I knew it was brand new!!! Great piece of kit, very quiet as well!Quote

29-08-2009, 08:33:11

JN
Quote:
Originally Posted by name='Kylevdm'
I have just installed on of these in my PC although, I almost died at the smell of new plastic from the bags when I opened it, at least I knew it was brand new!!! Great piece of kit, very quiet as well!
I have a fetish for that smell....mmmmm I can smell it nowQuote
Reply
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