X51 R2, problem rebooting while playing Final Fantasy XIV

I've been fighting these crashes for a couple years now with Final Fantasy XIV. It started before the Stormblood expansion came out. When changing zones or sometimes during cutscenes that might feature zone transitions within them, my PC will drop into a full reboot with no error screens. It is all very random it seems. I could have multiple crashes in a day, or not see any at all for a month. It can happen as early as during logging into the game, or not happen until hours later. It can happen whether the game is the only major program open at the time or if I have other things open as well. The event log offers no clues on the culprit, just giving the generic 'unexpected shutdown' type line. This is the only game it has come up with. I'm able to play other games such as Overwatch without issues.

Things I have tried in the past that didn't solve this:
- Updating video card drivers
- Lowering graphic settings in the game
- Doing a full uninstall/reinstall of the game
- Running the game on DX9 instead of DX11

I've tried watching my system temps, but nothing ever seemed out of the ordinary or sudden spikes that I can tell before it reboots. I don't have a large budget currently, so I'm unable to buy a bunch of parts to test and swap around, so anything that can better pinpoint the source here will help me out greatly.

Thank you in advance for all your time and help.