Crysis at its less graphics-intensive settings will give you a nice performance boost once you start to overclock your processor. The boosts are rather linear, as even the last step from 3.9 to 4.25 GHz was noticeable.
The same applies to Unreal Tournament 3. More CPU core speed translates into better game performance. The 28% clock speed increase (3.33 to 4.26 GHz) yielded 21% better frame rates, which is a great result.
Interestingly, the 3.6 GHz overclocked setting does not give you better performance, as the RAM speed drops a bit. Once you speed up to 3.9 or 4.26 GHz you’ll see a nice performance increase.