Okay, so I know alot of guys who speak with the results shown on the internet and blah blah...
I have a gt630, and i am not gonna rate it over 6670 since it is 2x, but I am not gonna say that it cant run games the way you want it,
First off, I played the Assassin's Creed 1,2,BH,RV, and 3 over all at highest with multisample 2x...Then comes deus ex: All at high with dx11 on and texture filtration again at 2x...now over GTA IV, I played it over high setting with texture filtration of 4x...
And, I played: Metro last light(high), Battlefield 2,3(high) , Sleeping Dogs(High), Far cry 3(high), Skyrim(med-high), Dishonored(Ultra), DMC 2013(ultra settings), Brother in arms hell highway(high), and mafia 2 at high settings as well.
So, whether you believe it or not, I have not had any complaints with it yet, but I will mention that it failed to run NFS rivals(which I believe was really badly programmed)