Depends on the resolution you play at. In resolutions like 1680x1050,you'll see a major bottleneck but on higher resolutions like 1080p,you won't see much of a bottleneck but overall,OC'ng your CPU will give you a good boost in some games.
ic. now i just use 720p resolution so do i need oc'ng my cpu clock around 3.00Ghz?
coz the perfomance just increase around 10% from my previous gtx260 most of games..