Corsair RM850x (2018) PSU Review

Our cross-load tests are described in detail here.

To generate the following charts, we set our loaders to auto mode through our custom-made software before trying more than 1500 possible load combinations with the +12V, 5V, and 3.3V rails. The load regulation deviations in each of the charts below are calculated by taking the nominal values of the rails (12V, 5V, and 3.3V) as point zero. The ambient temperature is between at 30°C (86°F) to 32°C (89.6°F).

Load Regulation Charts

Efficiency Chart

There is no region with efficiency exceeding 92%, however the 90-92% region is quite large. If the combined load on the minor rails was 100-120W, the unit's overall efficiency would be notably higher.There is no need anymore for so strong minor rails, after all.

Ripple Charts

Infrared Images

We apply half-load for 10 minutes with the PSU’s top cover and cooling fan removed before taking photos with our modified FLIR E4 camera that delivers 320×240 IR resolution (76,800 pixels).

The bus bars on the +12V board get quite hot, exceeding 110°C. This is natural since we push the PSU with 425W load for ten minutes without any active cooling, so those metallic bars have to take the heat off the +12V FETs. As it seems they do a good job since those FETs stay below 80°C. The bulk caps along with the filtering caps on the secondary side don't get too hot, so most likely the prolonged passive operation in this PSU won't create any problems on the long run.

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