Graphic intensive games like the good old Crysis relies heavily on GPU power and less on CPU so no worries there. But there's more to a game then eye candy so if u want better and faster physics effects, responsive ai and so on then u might want to overclock it a tiny bit. In one of my systems i'm running a E5200 (stock at 2.5GHz) at 3.3GHz (266 FSB from 200) with all settings on auto except my memory.
That small overclock should be done in a couple of seconds from your motherboards bios and it should be stable. Post your motherboard model for more details if u plan on overclocking
I overclocked to 3ghz, i tried 3.16 but i had a system failure. Dunno why.