Corsair HX850W (850w) ATX PSU

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 HX850W 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 HX850W 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 14.00A  0.75A  0.20A  233w /
213w  91.41% 24.5°C /
25.5°C 1.0°C 3.32v 5.10v 12.20v 5.07v  -11.86v Test 2
(Med)
8.75A 8.75A 28.00A 1.5A  0.40A  458w /
426w  93.01%  25.3°C /
26.1°C 0.8°C 3.30v
5.08v
12.18v 5.02v  -11.84v Test 3
(High)
13.12A 13.12A 42.00A  2.25A  0.60A  684w /
637w  93.12%  25.5C /
26.2°C 0.7°C 3.26v 5.06v 12.14v 4.98v -11.83v Test 4
(Full)
17.50A 17.50A 56.00A 3.00A  0.80A 930w /
848w 91.18%  25.5°C /
27.2°C  1.7°C 3.24v 5.04v 12.14v 4.93v -11.85v Test 5
(x-load)
17.00A 16.00A 1.00A 0.00A 0.00A  176w /
149w 84.65% 25.0°C /
26.1°C 1.1 °C 3.30v 5.08v 12.20v 5.11v -12.47v Test 6
(x-load)
 1.00A  1.00A  69.40A  0.00A  0.00A  910w /
850w 93.40%  24.5°C /
26.3°C  1.8°C 3.29v 5.06v 12.14v 5.06v -13.08v Test 7
(MAX)
 21.00A  21.00A 73.00A  4.50A  0.60A  1201w /
1084w 90.25%  26.4°C /
28.7°C  2.3°C 3.21v 5.02v 12.10v 4.85v -12.09v
 
Starting with tests 1-4 (the ones you’re most likely to see in real life) the HX850W has left me pretty much speechless. Not only was voltage regulation extremely tight all the way up to 848W load, but the efficiency…DAMN, the efficiency was simply amazing staying above 91% at all times. This clearly also had a knock-on effect on the exhaust temperature of the unit which rarely moved more than 1°C above the Intake temps, showing that there is VERY LITTLE energy wasted inside the HX850W during AC/DC conversion.
 
Moving on to the cross load tests 5 & 6, very little changed in terms of voltage regulation. In both tests the HX850W laughed in my face, keeping all rails totally in check like nothing was happening. Only in Test 5 did the testing manage to chip away at the stellar efficiency of the unit by bringing it down to 84.65%. Seriously though, this is still better than a lot of PSU’s can manage on a good day!
 
Finally in test 7 the HX850W was hooked up to both of our load testing machines to try and bring the unit to its knee’s. Did I manage it?…did I hell! With 21A on both the +3.3v and +5v rails and 73A on the +12v rail the PSU was still laughing at me while delivering rock solid voltages. That’s 1084W by the way, 234W more than what it says on the box!
 
In one last off-the-record attempt to get one over on the HX850W I hit it with everything it could take on the +12v rail. 91 AMPS was the read-out on the load tester before the PSU finally decided safely power off. Even then the voltage readout was 12.12v  right up to the end. Corsair – 1, Me – 0!
 
Corsair HX850W Results @ 50°C
   +3.3v  +5.0v  +12v  +5vSB  -12v  AC Watts /
 DC Watts
 Efficiency  Intake /
 Exhaust
Δ Temp Test 1
(Low)
4.37A 4.37A 14.00A  0.75A  0.20A  233w /
213w  91.41% 50.4°C /
49.7°C -0.7°C 3.32v 5.10v 12.20v 5.07v  -11.86v Test 2
(Med)
8.75A 8.75A 28.00A 1.5A  0.40A  460w /
426w  92.60% 51.2°C /
50.8°C -0.4°C 3.30v
5.07v
12.18v 5.02v  -11.84v Test 3
(High)
13.12A 13.12A 42.00A  2.25A  0.60A  685w /
637w  92.99%  51.9C /
52.4°C 0.5°C 3.26v 5.06v 12.14v 4.97v -11.83v Test 4
(Full)
17.50A 17.50A 56.00A 3.00A  0.80A 933w /
848w 90.88%  50.7°C /
51.5°C  0.9°C 3.24v 5.04v 12.14v 4.92v -11.87v Test 5
(x-load)
17.00A 16.00A 1.00A 0.00A 0.00A  176w /
149w 84.65% 52.0°C /
52.8°C 0.8 °C 3.30v 5.08v 12.20v 5.09v -12.47v Test 6
(x-load)
 1.00A  1.00A  69.40A  0.00A  0.00A  913w /
850w 93.09%  51.2°C /
52.5°C  1.5°C 3.29v 5.06v 12.14v 5.06v -13.06v Test 7
(MAX)
 21.00A  21.00A 73.00A  4.50A  0.60A  1206w /
1084w 89.88%  49.9°C /
52.0°C  2.1°C 3.21v 5.02v 12.09v 4.85v -12.09v
 
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 results might as well be classed as identical. It really is beginning to look like nothing I can throw at the HX850W can phase it in any way, shape or form.
 
Corsair HX850W 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
For the last part of the testing I analysed the ripple on the +3.3, +5 and +12v rails using a Rigol 25Mhz 400MSa/s oscilloscope. All readings were taken while the HX850W was installed inside the 50°C hot box to provide us with worst case scenario results.
 
Yet again the HX850W gave stunning results with the +3.3v and +5v rails staying below 10mV ripple in tests 1-6 and only hitting 12mV ripple in test 7. The +12v rail was also extremely clean with ripple starting at 10mV in test 1 and only increasing to 32mV by test 4. Test 7 saw the ripple hit 42mV, but this is still way below the maximum of 120mV as specified by ATX standards.
 

Now let’s move on to the conlcusion where I try to sum up everything seen today…