Game causes random restarts

So at some point, the game started causing my computer to restart. The first thing I did was check the Event Viewer for any critical errors; none were found, except for a critical error involving an unexpected shutdown. So I started suspecting component failure, particularly PSU or CPU; I monitored temperatures with the game open and found that the CPU was running hot; cleaned the heat sink and fan and the temperatures were at room temperature idle and not exceeding 65c under heavy load. However, upon loading up Overwatch the issue persisted. Flummoxed, I suspected that the PSU was failing. To be certain, I ran multiple stress tests such as defragmenting my hard drive while running Prime95 and Doom 2016 on Ultra settings. Doom was absolutely unplayable during this test, but the PC did not shut down in over six hours… So I had ruled out my computer; it’s old, but the components haven’t failed me yet.
What could it be then? I started tinkering around with my settings in-game and had the stupidest AHA! moment of my life: My frames were set to Custom with a limit of 300 FPS. The game was pushing my system well past its limits. THE PROBLEM IS I change this setting, close out the game, and when I load the game back up, it’s configured back to its old settings with the FPS limit at 300.

Anyway, the reason I made this topic is two-fold: if you’re experiencing frequent random restarts or shut downs, your FPS limiter may be the culprit; the other reason is to hopefully get some assistance troubleshooting the game defaulting to ridiculous settings every time I load it up.

Maybe this thread can help?

Yeah unfortunately I have to rescind my claims anyway; the issue still persists even with the frames capped at 60, and it seems to happen with increased frequency now… I still think it’s kind of strange that I can practically overload my computer to the point of complete unresponsiveness but this game somehow pushes it past the limits?

EDIT: Figured out the problem; I cracked open the case again and just poured over every square inch of hardware and noticed that my graphics card was not fully seated properly. Might also have been an issue with the RAM I’m using being different clock speeds, and the lower clocked stick couldn’t handle being overclocked.
Either way, I believe the issue is resolved.