You may also get lucky with a 3770K in regards to you get a chip that likes to cooperate, since every batch is not the same. This one may not get this frequency and good temperatures, but that other one may.
If you want the very high over clock of 5GHz, the 2700K is the way to go. If you're doing minimal overcooking, and want a tad bit higher performance stock, I'd go with the 3770K. The 3770K generally seems to get to get to 4.7GHz, or in that range.
Both with good aftermarket coolers though. The 3770K does consume a tad bit less power, but runs hotter under load overall. I can't recall if it runs the same temperature at idle however.
Which of these two processors will be best for gaming? i7-2700k
if you are converting videos using your onboard graphics 3770k will be useful otherwise go for 2700k .my personal opinion would be wait for the Haswell release becasue 3770k is a crappy chip it may draw less power but it runs very hot my idle temps using a corsair H80 is 34c .if u wanted to buy the cpu now go for 2700k if u are not using onboard video
Go with the Intel® Core™ i7-3770K while it may not overclock as well as the Intel Core i7-2700K. The 6% performance boost that the Intel Core i7-3770K has over the Intel Core i7-2700K at the same clock speed. In other words you can run the Intel® Core™ i7-3770K at 4.3GHz and get performance equal to that of the Intel Core i7-2700K running at 4.6GHz. When you match this up with the other featurest that the 3rd generation Intel Core processors bring to the table it is clear that the Intel Core i7-3770K is great processor that will serve you well.