HI All.
I thought I would pass on some learnings that might help those dealing with a similar issue.
I built up a high-spec rig about 2 weeks ago and have had nothing but problems with it. I've been building PCs since 2002 and this was a first for me!
Specs:
12900K
Z690 Gaming-F
2 x 16gb G Skill PC6000 DDR5 (won a Newegg shuffle)
EVGA 3080ti
2TB nvme boot drive on M2
The first day everything went pretty well - installed the 0811 bios via the FlashBack utility before ever booting in. Applied a fresh Win 10 Pro install, appropriately slimmed. Gained about 60fps in BF 2042 (coming from a 9900k) with similar gains in other CPU intensive titles. Then the decline began, escalating in frequency:
Total power-off reboots under load (most frequent) w/o a BSOD
Then random reboots at idle
Hard locks at idle
Handbrake re-encode hard locks almost immediately at start
Finally this morning the machine was hard locking & rebooting without ever getting to windows
Steps I took to solve:
Every BIOS tweak I could find, fiddling with power settings mostly as the symptoms seemed to point in that direction
Upgraded my PSU from a Seasonic 850W Prime Titanium to a Seasonic 1000W TX Prime Titanium (used the existing cables) with little to no change
Ran multiple instances of memtest, all passing at XMP1
Pored over Event Viewer for clues on the reboots & locks with no luck
Rethreaded power with the new cables with no change
Backed out of the XMP profile and this added enough stability to actually use the computer for a few hours
The solution:
I finally pulled the GPU and CMOS battery + jumped it to reset the memory. Booted into setup and reset to defaults. Made the small moves needed to get to basic working order, including setting the ram to XMP1 - solid ever since, even under load.
I've never experienced corrupted BIOS memory before and have been kicking myself ever since - seems like jumping the CMOS is the first thing every YouTube PC repair person does at the beginning of troubleshooting.
I actually have new parts being shipped to me in case this crops back up and will reply back if there is any change. Big thank you to everyone here that posts about their issues - it really helped me hone in and what feels like solving the problem.