Asus P5NE-Sli Motherboard AND
Asus P5KPL-C/1600 Motherboard? I don't think so.
Must be the P5N-E nForce 650i SLI with 2 9800GT video cards. GeForce 9800 GTs peform essentially the same as GeForce 8800 GTs.
If you have AA/AF turned on your performance will be marginal at very high settings. Try monitor resolution of 1280x1024.
Without filters it should run OK most of the time with occasional slowdowns below 30FPS. For better performance look for the Crysis Tweak Guides - the game still looks great at high settings and even medium-high settings.
(Core 2 Extreme QX9770 @ 3.20GHz / EVGA nForce 790i SLI / 4GB Corsair DDR3-1333)
(using HIGH settings with the shaders at very high, not the Very High settings)