Computer Restarting while gaming with Sapphire HD 7870

[gringo1987]

Hey guys.. i'm having a bit of an issue here which is really annoying me.. my pc runs fine, just built it.
Mobo: Asus m5a78lm usb3
CPU: FX 6300
PSU: Corsair VS550
GPU: Sapphire hd 7870 oc edition
Ram: 2x4gb Gskill Ripjaws

I have everything running stock, no overclocking at all. But when i play any game (mainly bf4) the computer sound loops and restarts after a couple of minutes max. I've found that if i downclock my gpu to the non oc settings (50mhz lower on both clock and memory) it works fine. that's one thing that annoys me. The other is that i can overclock the gpu both clocks up about 200mhz extra and run furmark and it passes with flying colours.. i've even tried aida64 stress testing all hardware at the same time and again, it passes with flying colours. Temperatures are fine and everything.. Could anyone enlighten me as to why my computer resets during games at factory oc settings on my gpu but works fine if i downclock 50mhz?

thanks in advance

 

[gringo1987]

I know it's late, but it turns out it was just a faulty gpu.. since then have changed to an r9 290 and i've never looked back since..