sorry for rezzing a dead thread but I'm experiencing a similar issue.
I have a custom watercooled system with the following specs:
ryzen 9 5900X
EVGA 2080 ti XC2 ultra with a vertical GPU riser
Asrock X570 Taichi on bios 4.0
Corsair Vengence rgb pro 4*8 at 3600 cl 16 (manually input the XMP profile)
Corsair RMx 750w that I had since 2017
sabernet rocket 4.0
2* sabernet rocket 3.0
3 2.5 SSDs
1 HDD
here is my issue, sometimes when I'm gaming the system does a hard restart ( the screen goes black and the system reboots with no error codes on the motherboard).
is this PSU OCP?
another issue is after a cold start (unplugged from the wall), the system does a detect hardware boot similar to when turning on the system for the first time.
this only appeared after draining my loop and my GPU block leaked water after cleaning it on the riser cable and card (I cleaned the card thoroughly and it scores pretty high in timespy, Graphics Score 16,602) recently so I think its the riser cable fault and I have a new one on the way.
this doesn't happen with benchmarks, only while gaming. it also happens about once a month where even after the hard restart it still occurs after launching the game and playing for about 5-15 minutes.
another thing that happens is after the hard restart windows no longer detects my pcie 4.0 ssd. I think also the motherboard bios doesn't detect it, last time this happened to me, the drive showed up in the bios but not in windows.
so far I have replaced and upgraded most of my components since this issue started. I upgraded to a pcie 4.0 from a 3.0 drive (I had 3 NVME 3.0 drives) that I thought was dying. I have swapped the rams from 3200 16x2 to 3600 8x4. I have upgraded from 3700X to 5900X.
one fix I found is to unplug my PC from the wall and reconnect it after the power drains from the PSU. this fixes my issue with the 4.0 drive not showing up in windows.
honestly I'm at the point where I think its either the motherboard or the PSU and I was wondering which one to swap.
any suggestions would be greatly appreciated.