When i play any game, for example LoL my FPS is 58-60 (Vsync) and after 5 minutes it drops to 45, then 35 and then 10, same with CSS, BF3 and all games i play. It can't be my graphics card i just upgraded it, maybe i should change my stock cooler with a better one? On idle my CPU is 30-40 celsius.
Sounds like overheating, possibly psu. What make/model is your psu? Run hwmonitor or gpuz to find your max gpu temp. Since you say you just upgraded your gpu it could be a driver issue. Did you remove the old driver before installing the new one?
Hey man, have you cleared this problem? Im having the same thing wondering whats causing it! My fps will be 80+ on BF4 then over time it gets lower and lower, then when I reboot the system my fps is fine again.