New Corsair RM850x PSU won't run a GPU that my old Corsair RM650TX can. Anyone got a clue?

BChaney

I'm working on a new system build and have been dealing with an apparent PSU/GPU compatibility problem. As part of the troubleshooting process, I'm testing a new RM850x on the existing system. This system has an RM650TX PSU and has a new MSI Radeon RX 6650 XT board that is slated to move into the new build. Everything works fine. When I swap to the new PSU, including switching to the new cables, everything powers up but no video. In further testing of the RM850x, if I swap out the new video card for the previous one, which uses 2 6-pin PCI-E connections rather than the 8-pin PCI-E the MSI board uses, everything works there.

I'm kinda stumped here. This is the 2nd RM850x I've tried for this build. I exchanged the first one thinking that it must just be defective, but the 2nd PSU acts the same. I've been using Corsair PSU's for years but it would seem that the RM850x simply can't run the new 8-pin RX 6650 XT board. Anyone have any ideas why this would be?

PowerSpec_MikeW

@BChaney

MSI card should use the same 6+2, but it only requires one. Was there some type of adapter included?

BChaney

The MSI card is indeed a single 6+2 socket. While testing I cycled through both 6+2 plugs on each of 2 different PCI-E cables and tried a couple different CPU/PCI-E ports on the PSU. Same result each time. No adapters were used/needed for any of the connection tests.

PowerSpec_MikeW

@BChaney

Do you have a motherboard with a debug LEDs? If so, are they confirming the GPU failure or something else?

BChaney

@PowerSpec_MikeW

Thank you for replying, Mike. I've since given up on the new build & returned everything. The weird PSU behavior was just one of a couple problems I encountered.