Shonovie :
I want to know what cooler I should buy for a 4.2ghz overclock. Should I get a water cooler? Or is my hyper 212 evo enough
you SHOULD be able to. I have a very stable 4.6GHz on the 6600k with an EVO 212 using a 1.29Vcore. Every piece of silicon if different, but you should easily be able to get 4.2 on the 6600k using the EVO 212.