This is overclocking. It's my E8400, C0 steping,does it performing good?

well if u know what u doin, den ur cpu go even faster, 4ghz with good cpu fan quite easy.

your processor is fast, why do you need to overclock it?

Co steping? do you mean Go Stepping. Its new from intel core 2 since it ran considerably cooler you can over clock your cpu a couple of hundred mhz. Just try your OC by step increment so you could avoid frying your cpu. Base from what i've heard from the forum some guy run a cool 3570 mhz from his E6650, and surprise how easy it was. Well good luck on you OC.

Hey, I don't really know how to answer your question, I don't really know much about overclocking. Hopefully someone else will be able to answer your question better than I have done, in a really good way so you can understand and benefit from it. Make sure you have a good day, Happy Lotting!!