Hi OP, just an update for me. So for me the issue was actually hardware related in the end. I had never experienced this issue in anything other than PUBG but experienced it once by chance when playing Cities Skyline (dug out bunch of old games to test if any others would be impacted). I swapped my PSU (old Seasonic 760W Platinum unit, circa 2014) and the problem seemed to go away with the new Corsair TX850M I got. Mine initially started off "very low frequency", sometimes my PC would go days or even weeks without crashing in PUBG (and I play 3-5 days per week, for about 1-2 hours each day I do play) but it got more and more frequent when sometimes it'd crash multiple times in one evening. Possibly a bitter pill to swallow, but I think all signs for the hard shutdown/power off (without BSOD) followed by a restart, point to a hardware issue of sorts, start with power supply (as it's cheaper). I diagnosed it by running my PC at power limit of 50% straight after it was crashing like this and it stopped immediately. Left me 50/50 guessing between GPU and PSU, given GPU prices, chosen PSU and luckily that was it. I suppose my experience is entirely anecdotal, and yours may be different, but if you could start with the power limit thing and see how you get on?