I know that the card is made for 65C constant temps, but temps above 120F are supposed to reduce a components lifespan by 50% and an additional 50% for every 10F increase. It could be that another component is messing up, how do you know it is the video card. It could just as easily be your ram. I would recommend putting another video card in the system to see if your fps is still messed up or to put your vid card in another computer. It is also possible that you have set: fps_max 50. You should have other games / programs to test your performance on.