Corsair RM850x Shift ATX v3.1 PSU Review

Epilogue

The Corsair RM850x Shift ATX v3.1 delivers excellent overall performance, achieving first place among the units in my comparison. It offers tight load regulation, strong ripple suppression, and a stable 12V rail even during transient loads. Efficiency is high across the entire load range, and it also provides a long hold-up time, low inrush currents, a highly efficient 5VSB rail, and very low vampire power. On top of all that, its operation is dead silent. This is one of the quietest 850W PSUs on the market today.

Unlike its 1000W sibling, the APFC converter delivered solid performance even at 230V, and, on top of that, the minor rails had good transient response under all conditions. Regarding the protection features, I noticed some issues there with the settings of the minor rails. Besides sky-high OCP triggering points, in comparison to the nominal values, I also found that the standard and high temperature OCP triggering points are almost similar, which affects their effectiveness. The PSU is stressed way more under high operating temperatures, hence there needs to be a significant difference in the respective OCP (and OPP) triggering points.

Lastly, you will probably notice a high difference in my inrush current measurements compared to previous reviews. This is because I completely changed the methodology and the measuring equipment. I used to switch the PSU on and off via its power switch, which affected the respective measurements. I do it now using an AC source, set to supply power starting with a 90-degree phase.

All in all, the Corsair RM850x Shift ATX v3.1 offers top performance and high build quality. If it weren’t for the protection feature settings on the minor rails, it could easily get a recommendation, even an editor’s choice, if I were in the right mood! But I made a promise a while ago, not to provide any badge to a PSU that doesn’t have correctly set protection features. I know that many in the industry will hate me for this, but I have to apply pressure somehow on this highly sensitive subject (PSU protection features).

Before investing in a new power supply, read my article on the Best ATX v3.x PSUs to compare all alternative PSU offerings. You help me a lot by using my affiliate links, which don’t increase the price of the product. I receive a commission from Amazon every time you do it, which can make a significant difference for me, especially now that I am working independently, exclusively for my media, rather than for someone else.

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