a 7770 is roughly on par with a 6850, the 6870 has the most grunt though. i had a 6870 and traded down to a 7770 for F@H purposes, but i dont notice the diff to much when i play games on that pc. Keep in mind that a 6870 will require 2 x 6 pin connections whereas a 7770 only needs 1 x 6 pin.