I have the true problem.
For some odd reason Crysis runs about twice as slow in SLI. Disable one of your cards and it will be better off. Trust me I used to have two 8600's and it solved it for me and apparently many other people from the forum I got it from.

After a second look I used to have that same EXACT setup.

It's because your power supply maybe weak.
I bought a new one and it works better

If you want, run it in windowed and all low settings. Still looks AMAZING in my opinion. Runs at about 30-40 fps constantly on my laptop...Lol... Still playable...Still fun...

Aleready solved. i play it on 1024x768 x2 AA all high fullscreen
about 30 fps

Or, you can turn AA off and play at a higher resolution. No need for it really, cuz higher resolutions reduce the jaggedness.

Higher res also means better looking models for more realisticness.