I recently upgraded the core components of a computer I built a few years ago. I replaced the motherboard, memory, and CPU and have been running into issues since
The problem I started running into (after my upgrade) is that after some period of time (a half hour to an hour) the computer will shut down. There are no warning messages or flags, it just abruptly shuts itself off. While it has happened under "normal" use (web browser, a few applications), it is almost guaranteed to happen during gaming.
1) I do not believe it to be a heat issue. I initially had problems with heat but recently re-installed the CPU heat sink using Arctic Silver 5, and have been obsessively monitoring heat since. Similarly, the GPU heat has also been fine. I've run Intel Burn Test and Furmark concurrently and neither CPU nor GPU exceed 70° C.
2) I do not believe it to be a PSU issue. I only know this because in an attempt to resolve this issue I just installed a brand new PSU that should have plenty of headroom for my system (600W, 40A single 12V rail). So the shut-down issue has happened with both power supplies.
3) I do not believe the memory is an issue - as I write this my computer is running Memtest86+. When I left for work it had been running for 9 hours and had completed 4 passes with no errors. I decided to let it go another 9 or 10 hours to get through a full 8 passes just in case, but I would be surprised if it finds any at this point. It's also worth pointing out that I checked in BIOS and the memory is currently running at its rated speed of 1600.
My question is: what's left? The RAM and GPU seem to be properly seated, Windows is up to date. What's left to check?
My specs are as follows, note that nothing is overclocked: