about 3770K and 2700K

Hi guys

this is my first post on this forum, so don't kill me just yet.

I just finished reading the "learning to live with compromise about the 3770K" and I'm little confused.

As I have browsed through the forum post I found that people had trouble getting the 4.5ghz mark but in the review/test they had no problem hitting 4.5ghz with stock cooler.

So I'm wondering how come it is hard to get to the 4.5ghz mark - I'm about to build a new rig and was hoping to do some OC'ing - and I can't really decide whether to choose the 2700K or the 3770K - I don't plan on using stock cooling as in my experience they are noisy as hell and can't normally deliver enough cooling.

So I'm looking at the AiO watercooling units from Corsair and NZXT.

Where I live the 2700K costs more than the 3770K, and my initial choice was the 3770K when I read the reviewer was expecting to hit the 5ghz mark - but is that at all possible ? i don't have a tank of liquid nitrogen lying around  

Anyone have any ideas ?

and just for the record I AM A COMPLETE OC NOOB!

Cheers

Nickolaj