I have a Clevo P15xEMx with a 7970M GPU and i7-3610QM CPU, whenever I run a graphic-intensive game, like GTA V, the game lags after a while, this applies for other games and apparently it's because the GPU's overheating, but after tabbing out and letting it cool, it still lags, what can I do about this? If I have to physically add cooling, what's the best way to do that?