DOOM 3
Note the lack of performance drop-off as the 7800 GTX scale to 1600x1200? XFX's even manages to break the 100FPS barrier! That said, the game is perfectly playable on an ATI RADEON X850 XT PE at this setting.
Added I.Q. forces even the mighty 7800 GTX to slow down some. Faster clock speeds win the day, so the BFG and XFX cards are top dog here.