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Download the Crysis 2 Tool (Crysis 2 Advanced Graphics Options)

RUN IT xD

The important options for you:


MSAA 0 Disabled
I think YOU MUST disable this. MSAA puts a LOT of performance impact. (not tested but tweaking can be done later on)

Edge AA 0 Disabled. I have also set this to disabled just to make sure it's really smooth. (I later on do screenshot comparison for myself)

That basically is all. I have also set the FOV to 80 but it's too fish-eyeish, just to warn you. 55 should be default.
I have also set MotionBlur to CameraAndObject since on "High" basically everything is on "Low".

With these two AA things diabled, I think everything can be set on high and it's still smooth.
Actually the game is running at 90fps in the outdoors (somewhere at the church where it's really hardware hungry)

I'M SO HAPPY AT THE MOMENT... I bought this 2nd HD6970 just to run this game great...and even with two 6970 it was barely playable @ 5292x1050 @ High just because of the hidden MSAA


Just as a reference.
Even if I set everything to high now, it should run like hell. I'll do this just now. (and lower FoV)

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oh and the second trick is as mentioned above, rename Crysis2.exe to Bioshock.exe or use the RadeonPro tool and set CrossfireX Tweaks under "Tweaks" to Bioshock.

Use both methods for maximum performance