Is good enough IMHO. I have the 2600K and I just have my bios at default with my ram which is 1600 rated running @1333 and I don't see the difference when playing MW3. I do see a difference if I bench mark for sure, but as I live in the real world when it comes down to gaming and everyday stuff, it's good enough. But I do have a GTX 580 Extreme Edition card as well.
If you do want to overclock, that guide I showed you will give you a pretty good idea!
But is it really worth it if you aren't a bencher? NO.