I brought an old(er) gaming rig back to life for my GF. It has two GTX 580's in it currently with a 1366 i7 970 and 12Gb of RAM. I was thinking of replacing the 580's with a single GTX 960. Would the GTX 960 be better than the two 580's? She plays at 1920x1200, and streams TF2 and Minecraft to twitch. I was thinking that for a lot of the odd ball games she plays that don't natively support SLI it might be better but I don't want to cut performance too much. I also want to upgrade her on the cheap for the time being.