Corsair CX850M 850W Power Supply

REVIEW INFORMATION
SUPPLIED BY: Corsair
MANUFACTURER: Corsair
PRODUCT: CX850M 850W
PROD LINK: Corsair’s Current Offerings!
PRICE: $119.99 @ NewEgg
Price is at the time of testing!

Time to get the fun started. I will be using the exact same test equipment as I did with the 750W model, which has gone unchanged for years now. I will be using my updated methodology, however, so be prepared to see the low load test integrated into the main tests.

CX850M 850W – STANDBY Load Tests
Test # +5VSB DC Watts/
AC Watts
Eff. P.F.
Load Tests
1 0.5A 2.52W/
3.18W
79.2% 0.237
5.04V
2 1.5A 7.52W/
9.71W
77.4% 0.404
5.01V
3 3.0A 14.9W/
19.6W
76.0% 0.473
4.96V

But first, the standby load tests. Nothing shocking here… this is the same platform as the 750, so we’ve got roughly the same efficiency results. Above average, but nothing groundbreaking.

Voltage regulation is very good at 1.6%.

CX850M 850W – Cold Load Tests
Test # +3.3V +5V +12V DC Watts/
AC Watts
AC
Input
Eff. P.F. Intake/
Exhaust
Progressive Load Tests
1 1A 1A 6A 85.5W/
105.1W
118.3V 81.4% 0.954 24°C/
28°C
3.32V 5.08V 12.04V
2 1.5A 1.5A 13A 175.8W/
204.2W
117.6V 86.1% 0.974 25°C/
33°C
3.31V 5.07V 11.99V
3 3.5A 3.5A 32A 419.9W/
481.9W
116.4V 87.1% 0.991 27°C/
43°C
3.27V 5.03V 11.91V
4 5.5A 5.5A 51A 659.3W/
778.9W
118.2V 84.6% 0.994 28°C/
48°C
3.24V 5.00V 11.80V
5 7A 7A 64A 826W/
1009W
116.0V 81.9% 0.995 28°C/
53°C
3.22V 4.97V 11.74V
Crossload Tests
CL1 15A 15A 0A 128.6W/
161.6W
119.1V 79.6% 0.966 28°C/
40°C
3.25V 5.00V 12.02V
CL2 0A 0A 70A 825W/
1007W
116.1V 81.9% 0.995 29°C/
51°C
3.25V 5.01V 11.72V

Here, you can see what I meant on the last page about my cold test ambient temperatures. Using only one SM-268, the top one, on an 850W unit causes it to run hot. The power supply is directly on top of it, separated by a wooden platform. Therefore, we have twenty-eight degrees at the fan grille by the time test five comes around. That said, the unit does seem to be keeping itself cool enough. I never heard the fan.

For an 80 Plus Bronze unit, I expected the unit to have a far easier time meeting those numbers than it actually did. Tests one and five require me to add my 1% allowance to them to get the pass, and I usually don’t see a Bronze having a hard time with that. Even so, the unit climbed to the Silver area in test three, so it’s not beyond usefulness at all. It’s a poor competitor to Corsair’s own Gold certified CS850M, of course, but that’s to be expected. The CS line is intended to replace this old CX line as Corsair’s budget range of units, and have rather unsurprisingly shown themselves to be better products in every way.

Moving on to the voltage stability, it’s obvious to me that this platform is now being pushed about as far as it’s willing to bend. We have 3% on the nose for the 3.3V rail, 2.2% on the 5V rail, and 2.5% on the 12V rail for an average of 2.6%. That’s two whole scoring notches down from “excellent” for me, but not what I’d call inappropriate for a budget unit. I’ll complain if it slips another notch down in the hot box.

Of course, that’s assuming this one doesn’t shut down in the hot box, which is a long shot at best. Remember, units lose all voltage stability scoring points from me in the event of an overtemp shutdown. Even more, if they happen to blow their line regulation while doing it, or just blow up in general.