you need to turn off power saving in power options .. though i just looked on my PC and cant find it. i have seen it before. Maybe its in the nvidia control panel. But yeah CS is mad old and it will not take much but like you said, it will think it doesn't need it then it DOES need it thats when you'll see choppiness .. so best to have it at full power (maybe turn it back off when your done playing that specific game or similar less gpu intensive games) so it save u some energy on your parents bill