iittopper
Wise Old Owl
^^ not much just a little. will try till 4Ghz not more than that. Thats y i'm thinking so much
4 ghz is nothing for i5 2500k , its a child play thing . My friend just changed the multiplier to 40 without changing any other thing , and he got a stable 4 ghz ..(though it may not be same for you) .
But if you know basics about overclocking then pushing to 4 ghz will not be a problem..