Computer shutdown during games.

[NumBezZeDz]

Sometimes it shutdown sometimes the screen freezes.
But for BF4, everytime the game finished loading my computer shutdown and reboot again.
Before the reboot, my GPU fan speed is at 100%. After the reboot, The settings went back to default. Im currently using a beta driver: 14.6. I installed the 14.4 non beta driver but for some reason it says in the information menu Catalyst Version : 14.6. Please help me out, is it the drivers' problem or the graphics cards' problem.
GPU: hd7990
CPU: i7 4770k
PSU: 1200w xilence
RAM: 16gb corsair vengeance pro

 

[NumBezZeDz]

Just fixed the shutdown problem, changing the cpu voltage thingy, but the game still freezes after few minutes of gaming