Question Mysterious rebooting issue ruining my new build

Apr 24, 2021
Hi there, first off I'll apologise because this post may be a bit long but I'll try my best to keep it concise. I recently built a new system for high end gaming and I'll post the specs below:

NVidia RTX 3080 Founders Edition
Intel i9 10900KF
32gb of Corsair Dominator RAM @ 3600mhz
MSI Meg Z490 Unify
Aorus AIO liquid cooler 360mm
Fractal Design Define 7
EVGA 850W Gold PSU

The issue I'm experiencing is that seemingly randomly while running games, the PC turns off and then reboots a second later.

I built this the other month and had this problem right away, and have since tried anything I could think of to solve it. I have flashed and reset the bios multiple times, rewired the system, made sure everything was seated right and so on. My temps are completely normal and the GPU doesnt exceed 70 degrees Celsius and the processor never over 60

I would normally assume it may be a faulty power supply, except for the fact that it seems to be certain games that cause the crashes and some that do not. However, some games that cause the reboot are not at all demanding (Risk of Rain 2) while other games run fine that are demanding (HITMAN 2).

The most baffling part to me is that HITMAN 2 used to cause the reboot every 5 minutes or so and then I did a clean install of the OS and it runs perfectly, but other games still cause the reboot.

It seems to defy all logic and I can't think of any more solutions. Any help would be greatly appreciated. Thank you