By any change is your GPU sagging even a little?
I had a pc go black screen and reboot on me a few times as the GPU was sagging just a little bit.
Getting a GPU support solved the issue instantly.
Test it out by getting something temporary to support your GPU or lay your pc flat and see if you have the same issue.
You can "temporarily" even use a toilet paper tube

Or something more permanent

Also there's a bunch of different other options out these, some more hidden then others.
