Overclocking the CPU for gaming performance is one of the most mistaken thoughts i see people have. It doesnt offer any benefit at all (unless its a game like WoW, as said). You will not even see an fps increase of 3 in the majority of games.
I would like to see your results though, would be interesting for WoW. My guess is that 25 man raiding would see perhaps a 10-15 fps increase. For most other parts of the World, i doubt there will be any fps increase at all.