Corsair RM850x White PSU Review

By Aris Mpitziopoulos
published

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Protection Features

Check out our PSUs 101 article to learn more about PSU protection features. Our protection features evaluation methodology is described in detail here.

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Protection Features
OCP12V: 82.8A (116.9%), 12.054V 5V: 33.2A (132.8%), 5.033 3.3V: 33.5A (134%), 3.312V 5VSB: 7.3A (243.3%), 4.88V
OPP1016.96W (119.6%)
OTP✓ (170°C ambient @ secondary side)
SCP12V: ✓ 5V: ✓ 3.3V: ✓ 5VSB: ✓ -12V: ✓
PWR_OKOperates properly
NLO✓
SIPSurge: MOV Inrush: NTC thermistor

The OCP triggering point at +12V is set properly, while the minor rails are a little higher, at around 135%. It seems as though the 5VSB rail is super strong; at 7.3A, the voltage levels are still within its limits. Over-power protection is configured well, at 120% of the PSU's maximum-rated capacity.

Over-temperature protection is set a little higher than usual in order to cope with the PSU's extended passive mode (when the minor rails aren't pushed hard, at least). The power-good signal is accurate, and short circuit protection is available on all rails.

The lack of a bypass relay for the NTC thermistor is strange for such a large platform. There's definitely room for one.


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Aris Mpitziopoulos
Aris Mpitziopoulos
Contributing Editor

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