Hi All, just in in case this is helpful to anyone.
I've been having the notorious, random, no warning, no BSOD, reboots, the same as others have reported over the years and I spent a few weeks trying various solutions from here and other forums. It didn't help that the reboots were typically days apart, always at night when I wasn't using the PC and there weren't any obvious problems when monitoring and logging with HWInfo64. Occasionally I would get the same WHEA errors, as reported by others, about individual cores, in my Windows System event log.
Under load and stress testing I had no errors and temps were fine. The system had to be idle for the reboot to occur. Specifically, if cores were allowed to enter C6 state, it would happen at some point in the week. If C6 was disabled and I modified my Windows power plan to not let the processor idle below 5%, then the system would be fine. No idea why I had to do both of these but hey.
After trawling the forums, what worked for me ( so far - been 5 days now ), was changing LLC from Auto to 3 in the BIOS and lowering vcore by 0.045V. An unexpected side effect is that multi-core boost clocks are 100MHz higher than they used to be.
Thought this might be helpful to anyone else with the same issue and had exhausted other possibilities.
MSI X670E Tomahawk MB
64Gb 5600MHz DDR5
NZXT C 1200W Gold PSU
RTX 4060
Win 11 23H2
Not using anything like Ryzenmaster, nor overclocking, BIOS is fully uptodate and on default settings. Chipset and system drivers are fully uptodate.
