I ran my Phenom 965 at 3.8ghz with the stock cooler never going above 57c in Prime for over 20hours, my case cooling was good, but with a small step up you should have no issues getting to around 4.0ghz. Even the Rocketfish will be a decent improvement, for the price might as well go for it, try it, if it doesnt work out oh well save for a Coolermaster heatsink. If it does work and you get the clock you want you only had to invest $13, seems like a no-brainer to me. You can also return it correct?