Skip to main content

Corsair RM850x White PSU Review

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. 

Primary Rails And 5VSB Load Regulation

Load Regulation testing is detailed here.

Image 1 of 8

Image 2 of 8

Image 3 of 8

Image 4 of 8

Image 5 of 8

Image 6 of 8

Image 7 of 8

Image 8 of 8

Hold-Up Time

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

Image 1 of 7

Image 2 of 7

Image 3 of 7

Image 4 of 7

Image 5 of 7

Image 6 of 7

Image 7 of 7

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.

Image 1 of 2

Image 2 of 2

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.

Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan SpeedPSU NoiseTemps (In/Out)PF/AC Volts
15.196A1.982A1.982A0.996A84.56186.551%0 RPM<6.0 dB(A)46.18°C0.968
12.122V5.039V3.325V5.019V97.70138.31°C115.16V
211.404A2.975A2.977A1.196A169.03590.208%0 RPM<6.0 dB(A)46.81°C0.988
12.115V5.037V3.323V5.015V187.38338.43°C115.15V
318.022A3.473A3.460A1.397A254.17291.172%0 RPM<6.0 dB(A)47.26°C0.993
12.107V5.036V3.321V5.009V278.78238.69°C115.03V
424.648A3.971A3.975A1.599A339.40491.300%0 RPM<6.0 dB(A)48.35°C0.995
12.099V5.035V3.319V5.004V371.74538.99°C114.92V
530.951A4.966A4.971A1.800A424.71091.024%0 RPM<6.0 dB(A)49.07°C0.995
12.091V5.033V3.317V4.999V466.59239.06°C114.89V
637.202A5.961A5.970A2.002A509.25690.493%610 RPM10.2 dB(A)41.99°C0.996
12.082V5.032V3.314V4.995V562.75957.90°C114.77V
743.522A6.957A6.970A2.204A594.56489.918%655 RPM11.2 dB(A)42.50°C0.997
12.074V5.030V3.312V4.991V661.22860.01°C114.74V
849.858A7.953A7.973A2.407A679.92689.206%785 RPM18.1 dB(A)43.01°C0.997
12.065V5.029V3.310V4.987V762.19861.87°C114.61V
956.596A8.457A8.462A2.407A764.88588.453%943 RPM24.5 dB(A)44.22°C0.997
12.057V5.027V3.308V4.986V864.73364.15°C114.47V
1063.080A8.955A8.984A3.019A849.69387.554%1154 RPM31.0 dB(A)45.81°C0.997
12.048V5.025V3.306V4.970V970.48265.96°C114.44V
1170.165A8.957A8.989A3.020A934.49086.591%1415 RPM36.7 dB(A)47.43°C0.997
12.040V5.024V3.304V4.968V1079.19569.43°C114.29V
CL10.729A18.002A17.999A0.000A159.01683.428%785 RPM18.1 dB(A)44.25°C0.989
12.095V5.029V3.315V5.068V190.60361.86°C115.13V
CL270.830A1.000A0.997A1.000A867.18587.882%1119 RPM30.0 dB(A)45.60°C0.997
12.055V5.028V3.308V5.004V986.75866.48°C114.42V

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).


MORE: Best Power Supplies

MORE:How We Test Power Supplies

MORE:All Power Supply Content

  • 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