My i7 4790K does 4.8 Ghz with 1.265 vcore.
My LEPA aquachanger 240 keeps my temperatures between 69 and 77 (core temperatures: 75-77-76-69)
I've read of many people needing 1.35 or higher vcore to hit 4.8 though(Which is quite a bit higher than safe). I think my chip is definitely on the high end of the spectrum. I also have my Uncore ratio up to 4.4 with only 1.05 vring.