Thanks, it looks like all of the WHEA error records have been corrupted. As you already know, the issue is going to be due to some form of hardware failure, while troubleshooting, please ensure that you aren't overclocking any components and your BIOS settings have been set to their factory defaults.
Let's begin with your testing your RAM with MemTest86, please ensure that you run it for 8 passes (2 sets of 4 passes):
Test RAM with PassMark MemTest86 (version 7.4 was used)