Overclocking performance

so i just got my Core Contact freezer ( the #1 heatsink rated by many sites) and am planning to hopefully overclock my Q9300 on my evga 780i SLI from 2.5 stock to 3.0 and was wondering what kind of performance increases i should see in games. since most games dont support quad cores im pretty much running a 2.5 dual core ATM. so thinking this way, im wondering if ill see a good fps gain in crysis and some other cpu demanding games.

Don't expect more than 10.

But the rest of your comp will run noticibaly faster.