I decided to retire the tried and true 3DMark 2006 as it seemed the processor was more of a limitation than the GPU at this point. As such, I started with the updated 3DMark 2011 which can be seen below.
As expected, each card scales very well in relation to each other. The 580 showed the biggst improvement when overclocking, however.
Furmark again shows a marked improvement when overclocking the 580. Of course keep in mind that the 560 came with a nice overclock from the factory, and the results shown under the overclocking category here are in addition to those already high clocks.
Crysis is a title that's starting to show its age, although it still works reasonably well for benchmarking purposes. The game is playable across all cards although if you really want to crank the eye candy up and avoid lagging, the 580 represents a good choice when overclocked at nearly 50 FPS at 16xAA.
Crysis 2 offers far superior graphics to the original with the high res texture pack and DirectX 11 support. The title even runs smoother than the original, proving that the original was likely coded poorly to begin with. Turing on 4xAA only dropped the average frame rates around 5 FPS on the GTX 580.
Farcry 2 is another dated game but this one really scales well with higher powered graphics cards. The Dunia game engine used in Farcry 2 is less demanding on hardware than the Cry Engine 2 used in Crysis and as such, the game is fully playable at max settings under every configuration.
Mafia 2 is another game that is fully playable across all cards. Do note that while I did use max graphics settings, PhysX was disabled. Enabling High PhysX dropped frames on the stock clocked 580 nearly 70 FPS.
Let's move ahead and wrap things up with a conclusion.