Your system is better than mine, and I run with everything on High just fine. So you probably have some kind of bottleneck going on that can be fixed.
Have you tried the following:
1) Try using Directx9, and install CCC for Warhead.
2) Try turning off one of the SLI video cards. Crysis is tuned for SLI/Crossfire, but this is a problem on many games.
3) What map are you using as your benchmark? Kagoshima is a beast, and ruins even the best systems. not the best choice for a benchmark unless you are the only one on the map.
4) Double check to ensure nothing is gobbling up resources running in the background. Antivirus, punkbuster, etc.
5) Defrag the hard drive?