I had this same problem with computer restarting, i removed one of my side fans and my computer hasnt reset itself since. That little box in ur top corner of ur case is ur power supply, please dont do anything to that. Try disconnecting any fans u might have (disregard ur cpu and power supply fans), then plug them back in slowly like others have recommended. You should have 2 big of a heat problem, hell i got 10 fans in my case, i disconnected one, no big deal. Yeah so i recommend the fan option as the culprit.