HD 7770 and GTX 650 are of same type.But HD 7770 is slightly better than GTX 650 and less priced than GTX 650,.I have Sapphire HD 7770 1gb GDDR5 and i can play all games at high-med settings..Here are some frame rate details
Battlefield 4 at ultra anti aliasing off - fps 35+
Far Cry 3 ultra - fps 40+
Watch Dogs Med-High settings,fxaa - 25+fps (this game is bad pc port)
Crysis 3 ultra anti aliasing off - 35+fps
fifa 14 ultra 60+fps
and i played many games and i cant list all of them here.It is really a good budget card...And you can play even the high expected game GTA V (releasing on november 14 for PS4,XB1 and PC) on med-high settings.Better go with the HD 7770.You may get extra 2-4 fps with HD 7770 and you can overclock it tooo...I overclocked it to 1100 from 950MHz,.and select it as best solution if it helped you.Any more doubts ,PM me....always at your assistance