what attract me about the HD 7770 is the power consumption, but im worried if they sacrificed the performance for power consumption because of the 128bit? I'm looking also for the EVGA 01G-P3-1556-KR GeForce GTX 550 Ti retail at http://www.newegg.com/Product/Product.aspx?Item=N82E16814130625
compare this to the HD 7770 which is far better superior?
7770 should be faster. IMO you should not worry too much about power consumption. your psu was strong enough to handle power hungry cards such as GTX580. as i mention earlier your best bet would be 6850, 6870 or GTX460 for your price range