Computer Reboots only when trying to play games

[Abanahasky]

Sense yesterday... I bought a game called rome 2 total war and i was able to play it for as long as i wanted, then it started every like 3-4 minutes in a game it would reboot automatically, Now its when i launch the game it reboots.. I tried launching a game i played flawlessly and the second the game loaded into a match the computer rebooted...I even tried doing a GPU stress test benchmark and the second i hit "Go" the computer reboots...im hearing that this could be a bad powersupply but i need to know this for sure so i can return the one i have and get a new one, I have a gtx 780 in my computer and a 650 watt powersupply by corsair, The minimum wattage was like 600 for the Graphics card i don't understand whats wrong with my computer or how this is happening to my dream machine

 

[hang-the-9]

Most likely either bad power supply or the video card. It "may" be the ram but that more often causes crashes in more than just games so it's pretty unlikely. To rule things out you'd have to either test a similar model in your computer or try your parts in another computer.