Inspiron 660 Win 10 Restarts when Gaming!

Hi guys! In desperation, I made an account here in hopes of solving my problem.
Had an Inspiron 660 for three years now and it has been amazing until this very week. Until now I was able to play Skyrim on Ultra without issues, now I cannot even run any small pixel game without my computer restarting on me for no reason.
I have completely reset my computer back to the original Windows 10 state, erased every file and app, and still it persists whenever I try to play a game. Friends have suggested it may be a power supply issue, what do you guys think?
And yes, I cleaned it out today of all the dust.
Please, please help a fellow Dell lover. Fallout 4 is coming, and I need to play it!