Hello. I have recently bought a new graphics card, a GT 640, and after a while of use, I have this awful lag problem. Everything lags, including windows itself! I used to just re-install the graphics card drivers and then don't do the restart afterwards, but now that doesn't work. I have tried restarting the computer and no luck! Please help me!!! I think it may be a drivers conflict, but I really don't know as I cant find any other drivers.