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Load Regulation, Hold-Up Time & Inrush Current

To learn more about our PSU tests and methodology, please check out How We Test Power Supply Units.

Aerocool ACP-850FP7

Corsair HX850

Corsair HX850i PSU

Primary Rails And 5VSB Load Regulation

Load Regulation testing is detailed here.

Image 1 of 8

Hold-Up Time

Our hold-up time tests are described in detail here.

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The hold-up time we measure is long at 30ms, and the delay between the power-good signal and hold-up time is pretty large, ensuring the system's safe shut-down.

Inrush Current

For details on our inrush current testing, please click here.

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With 115V input, the inrush current is quite low. It's a little higher than expected (but still fairly normal) with 230V input.

Load Regulation And Efficiency Measurements

The first set of tests reveals the stability of the voltage rails and the RM850x's efficiency. The applied load equals (approximately) 10 to 110 percent of the PSU's maximum load in increments of 10 percentage points.

We conducted two additional tests. During the first, we stressed the two minor rails (5V and 3.3V) with a high load, while the load at +12V was only 0.1A. This test reveals whether a PSU is compatible with Intel's C6/C7 sleep states or not. In the second test, we determined the maximum load the +12V rail could handle with minimal load on the minor rails.

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Test #	12V	5V	3.3V	5VSB	DC/AC (Watts)	Efficiency	Fan Speed	PSU Noise	Temps (In/Out)	PF/AC Volts
1	5.196A	1.982A	1.982A	0.996A	84.561	86.551%	0 RPM	<6.0 dB(A)	46.18°C	0.968
12.122V	5.039V	3.325V	5.019V	97.701	38.31°C	115.16V
2	11.404A	2.975A	2.977A	1.196A	169.035	90.208%	0 RPM	<6.0 dB(A)	46.81°C	0.988
12.115V	5.037V	3.323V	5.015V	187.383	38.43°C	115.15V
3	18.022A	3.473A	3.460A	1.397A	254.172	91.172%	0 RPM	<6.0 dB(A)	47.26°C	0.993
12.107V	5.036V	3.321V	5.009V	278.782	38.69°C	115.03V
4	24.648A	3.971A	3.975A	1.599A	339.404	91.300%	0 RPM	<6.0 dB(A)	48.35°C	0.995
12.099V	5.035V	3.319V	5.004V	371.745	38.99°C	114.92V
5	30.951A	4.966A	4.971A	1.800A	424.710	91.024%	0 RPM	<6.0 dB(A)	49.07°C	0.995
12.091V	5.033V	3.317V	4.999V	466.592	39.06°C	114.89V
6	37.202A	5.961A	5.970A	2.002A	509.256	90.493%	610 RPM	10.2 dB(A)	41.99°C	0.996
12.082V	5.032V	3.314V	4.995V	562.759	57.90°C	114.77V
7	43.522A	6.957A	6.970A	2.204A	594.564	89.918%	655 RPM	11.2 dB(A)	42.50°C	0.997
12.074V	5.030V	3.312V	4.991V	661.228	60.01°C	114.74V
8	49.858A	7.953A	7.973A	2.407A	679.926	89.206%	785 RPM	18.1 dB(A)	43.01°C	0.997
12.065V	5.029V	3.310V	4.987V	762.198	61.87°C	114.61V
9	56.596A	8.457A	8.462A	2.407A	764.885	88.453%	943 RPM	24.5 dB(A)	44.22°C	0.997
12.057V	5.027V	3.308V	4.986V	864.733	64.15°C	114.47V
10	63.080A	8.955A	8.984A	3.019A	849.693	87.554%	1154 RPM	31.0 dB(A)	45.81°C	0.997
12.048V	5.025V	3.306V	4.970V	970.482	65.96°C	114.44V
11	70.165A	8.957A	8.989A	3.020A	934.490	86.591%	1415 RPM	36.7 dB(A)	47.43°C	0.997
12.040V	5.024V	3.304V	4.968V	1079.195	69.43°C	114.29V
CL1	0.729A	18.002A	17.999A	0.000A	159.016	83.428%	785 RPM	18.1 dB(A)	44.25°C	0.989
12.095V	5.029V	3.315V	5.068V	190.603	61.86°C	115.13V
CL2	70.830A	1.000A	0.997A	1.000A	867.185	87.882%	1119 RPM	30.0 dB(A)	45.60°C	0.997
12.055V	5.028V	3.308V	5.004V	986.758	66.48°C	114.42V

Load regulation is pretty tight on all rails; everything except the 5VSB rail stays within 1% (and even then, 5VSB achieves 1.31% deviation, a new load regulation record for the 850W PSU category).

Efficiency-wise, the RM850x easily meets 80 PLUS' requirements for Gold certification, even under our hot box's very high ambient test conditions. Fan noise stays low not only because of its limited maximum speed, but also thanks to a relaxed profile. We have to push the PSU beyond its limits to make the fan spin at full speed, where it barely hits 37 dB(A).

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Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.

10 Comments Comment from the forums

stairmand

I've got one of these and wish I had bought a different PSU and paid for cable mods instead. The in line caps are not too big a deal (lets not forget the whole point of the colour and cables IS the aesthetics) but the way the PCIe cables are wired (in a Y config) is terrible and makes it very hard to neatly cable.

The combes are also relatively poor quality and don't clip together brilliantly especially as there are multiples wires used in a couple of pins.
Reply
vapour

Looks nice, but seems to behind Seasonic Focus Point and EVGA Supernova G2. Make better psus, Corsair!
Reply
feelingtheblanks

Hey Aris,

Is there a possibility to retest one of those Evga Supernova G2 units, like G2 750, in terms of the new hold-up time tests?

I read your Leadex Gold 550 review, where you find out the hold up time of that unit (and maybe the whole platform) is questionable and not really safe. So that made me think that the rest of the platform and also the Evga units are plagued by the same important mistake.

I own a G2 750 and after reading that review and some forum threads, I'm a bit worried now.

Hope you can help.

Best
Reply
turkey3_scratch

20451514 said:
Looks nice, but seems to behind Seasonic Focus Point and EVGA Supernova G2. Make better psus, Corsair!

RMx have always been better than the G2 because they're quieter.
Reply
Aris_Mp

Unfortunately I don't have any G2 units any more, to test for hold-up time.
Reply
feelingtheblanks

20453647 said:
Unfortunately I don't have any G2 units any more, to test for hold-up time.

Thanks for the answer Aris,

Do you think that these units are safe though? G3 850 seems fine on your tests. Are there dramatic differences between G2 750/850 and G3 850 in terms of bulk caps etc...? You have a rough estimation maybe?

Best

Reply
Aris_Mp

I believe that the G2s are pretty good units and I would't hesitate to use them. Unfortunately I cannot estimate their hold-up time without testing them (something impossible now since they are EOL).
Reply
turkey3_scratch

20454054 said:
20453647 said:
Unfortunately I don't have any G2 units any more, to test for hold-up time.

Thanks for the answer Aris,

Do you think that these units are safe though? G3 850 seems fine on your tests. Are there dramatic differences between G2 750/850 and G3 850 in terms of bulk caps etc...? You have a rough estimation maybe?

Best

I looked into it before. The 650 G2 most likely has the problem where it drops the PWR_OK signal after the voltages go out of spec. The 550W should be fine. I'd assume the 750W is perfectly fine also. Not something to worry much about anyway.
Reply
YoAndy

My previous corsair GS700 fried my motherboard(lasted only 2 years of mild use)..
Reply
turkey3_scratch

20454749 said:
My previous corsair GS700 fried my motherboard(lasted only 2 years of mild use)..

Pretty sure those were some of the most unreliable units in history. RMA rates above 10% I believe.
Reply

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