Upgrade from Phenom II 550 to 965. Worth it?

[exls08]

I recently bought 2 x 5870's. I expected this to run Crysis and Crysis Warhead very well like benchmarks online said (enthusiast, 8 aa). But the frames i got were less than impressive. There were many stutters during gameplay and frames dropped below 30 at times. I heard that it is because of my processor bottlenecking the game but i am not sure. How much of an improvement would i see from upgrading my phenom ii 550 to 965? i already tried unlocking the cores but no luck, they are faulty.

Specs
phenom ii 550 oc at 3.6
2 x 5870 crossfire
4 gb ram ddr3 gskill 1600