If you change to that cpu, you need to change the mobo also because it's the new socket (lga 1150.)
If you want to upgrade to a k (for overclocking) I think the core i7 3770k would be in the same price range and better performance. I recommend A k for overclocking.
didn't really answer my question. I'm aware the 4770k uses a new socket thats not the problem though. Mind taking a closer look at my questions? on Newegg the 4770k and the 2600k are literally the same price, so the 3770k is out of the question right now
The difference between the 2600 and the 4770 isn't going to be a huge jump - at most maybe 20%. In most situations, probably less than 10% difference between the two.
That being said, if it were my system, I wouldn't spend the money on the new motherboard and CPU for that small of an increase.
As for overclocking a non K CPU. You have to have the right motherboard to allow for it (usually a Z series board). Also, you can only change the BCLK frequency. Which you are lucky to get over a 5% increase from. It's honestly not worth it.
If you could trade your 2600 and motherboard for a 4770 and motherboard you would be stupid not to.
If you were to swap it would be an unfair trade in your favour I'd bet.
The 2600 is locked, whereas the 4770k is not.
2600 is sandy bridge (can OC higher) and the 4770k is haswell which does have some performance boosts just due to newer technology since sandy bridge (don't know details, but I've heard things like sandy->ivy 15% boost-> Haswell 5% boost, don't quote me on that).
I don't understand your situation though; why are you looking for a 4770k when the 2600 is perfectly capable? And the 4770k isn't compatible with your mobo?