A single GTX 770 anyway. CrossFire has multiple issues like micro stuttering , flicker , heat , noise. A GTX 770 on the other hand will run quite , have less heat , no issues. You might be interested in a HD 7970GHz as well. AMD's Never Settle Reloaded offer will give you 4 games as well. So the choice is yours. Always Remember , 2xMid end GPU < 1xHigh end GPU.