Maybe its the game? Are you having this problem on any other games? Also, like I said before, might also be your GPU trying to conserve power as well, as it is at 99% usage. So it might be trying to use up less power and well perform not as well as to not max itself out... Just an assumption 😛 I would reccomend upgrading your card anyways, as its not even that good for newer games coming out. You could also try getting a 2nd, and running the game in crossfire. 😀