There is no set speed that every 2700k will get, every cpu is just a bit different and you have to go through the overclocking process to see what speed your cpu reaches and is stable at. From the people that have posted here and other places they get between 4.5ghz and 4.9ghz, a few have gone past 4.9ghz but those few have exceptional cooling and many years of overclocking experience. With just using air for cooling I would say that you could reach 4.5ghz, but you need very good thermal compound and it has to be applied right and the case will have to have very good air flow.