O my god !!! 8400 GS outperform 7970 ?? Ill give you an 8400 GS and give me an 590gtx
From what reviews did you get that ?
If you can play Metro 2033 and other high demandings games with 8400 GS and with even wors 7400 GS i'll eat that cards.
For your knowledge those card are outdated for a long time. And the worst thing is the GS are the weakest from a series.
Exemple : 9800gs <9800GT<9800gtx and after that camed 9800gtx+