That might be what she said, but seriously, there is a particular room in the WSP that will always, and I do mean always, every time im in it for more then 30s, turns off my PC.
The room I am talking about is the big main room with 2 levels, all the graffiti, PCs, food stacks, and the escalator to the roof, over on the east central side of the WSP. Typically there is a 'kill the 3 waves of enemies' event in there, and a 'protect the SHD terminal' event, and literally every....single....time.....I go in there to do that mission, I run in, trip it, hop on my favorite wall and prepare for Showstopper goodness, then *boop* off goes my PC, either just as or just prior to the show getting started.
Soo, is that room borked or what? It isnt 'my PC overheating', my PC is blowing out cold air lol, my cooling is fine. 4-5 new fans, got an AC in my room lol, yeah my PC runs plenty cold. Another thing that turns off my PC is exposure to the fire particles, and sometimes explosions. Does this game have really buggy particles or something?
Assuming it isn't an unstable overclock or the system overheating then I'd suspect either GPU drivers (if not on the latest try the latest, if on the latest maybe try 1-2 versions back) or maybe that room is demanding more from the system for some reason resulting in higher power draw and your PSU isn't upto it.
On a related note some people have had issues like this in combination with Firefox and hardware acceleration and the FF 60.0.1 update is causing some GPU driver instability issues for some people.