So I built a new computer for my cousin in July. Everything ran fine, until he played some games on it, and then it would randomly shutdown while playing. Over a day or two the crashes became more frequent, so I told him to update the GFX drivers. Following this, the computer would shut down when launching the game. I assumed it was the drivers, but changing them back with the CD it came with didn't fix anything. Eventually the computer started shutting down while I was looking for ways to fix it, to the point where it would shut off during start up. I RMA'd the GFX card, but the new one did the same thing.
CPU: Intel core i5-4670K
MoBo: Asus Sabertooth Z97 Mark2 ATX LGA 1150
RAM: G.Skill Sniper series 2 x 4GB
GFX: EVGA GTX760 4GB