Running a COOLER MASTER Hyper N 520. I am pretty impressed with it so far. Also it is smaller than most high-performance air coolers only with 92mm fans so the size is not so much an issue. I am running a very slightly OC'd core i7-920 at 3.2Ghz currently. Temps are about 37-40C idle and 71C max at load. The max I determined by running LinX overnight and this is as high as it got. For general computing and game playing it may get as high as mid 60's but no more. See link below to see the cooler I purchased.