Going to have to run a battery of tests. Whatever you do, do NOT run small FFT AVX prime95. Only use AVX as I instruct here below..
First, download prime95 29.4 https://www.mersenne.org/download/
Run it then close it then open the file LOCAL.TXT and add these lines at the top:
Grab HWinfo64 (another nice program) while you're at it and have it running the same time as prime95). https://www.hwinfo.com/download/
Now you can do some more reasonable tests.
First do a CPU core reliability test by doing a small FFT stress test. This will put a strong load on your CPU without it getting out of control. Don't let it run 12 hours. I personally find that you don't need to let it run more than 30 minutes, as it can test the entire 8k-16k range by then. But if you really want to be sure, you can run it an hour. Have the program HWINFO64 running and look at the bottom for WHEA or CPU L0 errors also.
If that passes, now do a Vcore reliability test by running a custom test, checkbox "run FFT's in place" and enter 1344K-1344K for the range.
This stresses vcore stability more than heat stress. You absolutely MUST pass this test. 1 hour is enough for this. Half hour if you're in a hurry.
Then when you're done, you can stress the computer's IMC and main memory by doing a custom test, uncheck FFT's in place, and enter range 512K-4096K and set the memory size to 75% of your system memory. Example: if you have 32 GB of RAM, the total is 32768, so set it to 24576. For 16 GB, it's 75% of 16384. Ezpz.
This test will take much longer to do. Might have to leave it running overnight as this tests a lot of ranges now.
Finally, you should test the AVX stability test. This is similar to the 1344K test.
Open the file local.txt and change the 0 to a 1 for AVX.
Do not change FMA3.
Then run the same 1344K (don't forget to checkbox in place fft's) and it will run with AVX. This may run a bit hotter than small FFT without AVX (oddly enough it runs cooler on a 9700K and 9900K), so let it run for up to an hour.
Always monitor HWinfo64 for WHEA errors or CPU L0 errors if a thread doesn't crash.
This will take you awhile. Post your results when finished.