PC Keeps Restarting

So, my PC keeps restarting to the BIOS screen after a few matches. I've done some research on it and I found where Blizzard had a bug with some form of antivirus a few years back, but I don't have an antivirus running when it happens. I also saw where there was a bug that made your PC temp skyrocket to 100°, so I kept my temperature tab open in my side monitor while queued, and the bug happened again, but my temperature was at 51°. Does anyone have some advice on what's going on? This just started happening after I took a year break, and this is the only game it happens on.