I have a strange issue with a new system comprising of Ryzen 3700X and ASUS TUF X570 (WiFi).
I was able to boot the system, install Windows on an NVMe and then start and run Windows. After a couple of days of use the system shut down unexpectedly. From this point onwards I have not been able to fully boot any operating system. Windows on a known working HDD, the new Windows NVMe install, a Windows USB Recovery and Ubuntu on a seperate HDD all fail to boot.
Concerned that I had something loose I reseated every connector in the system. I then replaced the GPU with a different working GPU in a different PCIe slot. I reseated the memory, tried running with a both single sticks in different ports. I also used a different known working PSU, detached all external cables other than a single keyboard, DisplayPort, and internal NVMe/USB Boot Drive. The problem persisted.
Finally I managed to run Memtest86, on the default configuration the tests would run for a few seconds before creating a stream of errors and ending due to too many errors, hanging, or resetting the system. Often the errors identified a single CPU (14) as the issue.
I then ran Memtest on single CPU mode, this passed fine for all cores 0-13, but 14 and 15 always hung immediately. My BIOS allows the CPU to run in 2, 4, 6 or default(8) core mode, after selecting just two cores I can again boot and run the OS.
I assume these issues are pointing to a chipset issue, without swapping the motherboard or CPU, is there a way to determine which is at fault? How much does the motherboard take part in core selection and memory management on such a system?