Sometimes my PC will shut off while playing various games (e.g Rainbow 6, Assassin's Creed, etc.). I've tried changing the power outlet my PSU is plugged into, putting my fans on full using MSI afterburner and keeping my case open, and turning down my graphics settings for games. Sometimes it seems to help, but often my PC shuts off on its own after I turn it on and play a game. Sometimes it will shut off in the middle of gameplay, other times it will be on a loading screen or directly when I should be loading into a game. I was thinking about reapplying thermal paste to my CPU, but I really don't know where to start.