PC going to sleep randomly when playing games?

TaipaN_1

Prominent
Jun 30, 2017
1
0
510
Hey guys, im bit of a PC noob but here is my setup;

CPU- AMD FX8350
GPU- AMD R9 290X
MoBo- ASUS Sabertooth 990 2.0
Corsair liquid Cooled
1300 WATT Power supply
Corsair Vengance 16GB RAM

When im playing Arma 3 for a while out of nowhere the PC will go to sleep, like it full turns off and I have to hit power button to turn it back on and play (still in game because SSD). Then randomly it continues to do so sometimes after 10 seconds sometimes after a few more minutes i cannot figure out why, the CPU temp has never gone above 59 degrees celcius @4.8GHZ and never above 35@4.34GHZ. GPU usually sits around 60degrees give or take because I have MSI afterburner running on auto to control fan speed as required. Please any ideas as to why this is happening guys