I've been looking to upgrade my graphics card for a while now, and my friend just recently got a GTX 760, he can run any game on Ultra graphics (At least, that's what it seems like) but I can hardly run Arma 2 OA on High. I'm looking at a GeForce GTX 660, it seems really good for it's price and i'm most likely going to purchase one soon. The only problem is, I don't know if it is compatible with my computer. I currently have an AMD Radeon HD 7800 Series, so, is the GTX 660 Compatible? Or do you guys need some more information.