When testing Crysis 2 at 2560x1600, both the standard and overclocked GTX 680s averaged 32fps, which is precisely what the HD 7970 achieved as well.
The GTX 680 was 11% and 21% faster than the HD 7970 and the GTX 580 when running Dragon Age II at 2560x1600, while the Phantom card provided a 3% gain.
