Personalty I would get the COOLER MASTER Hyper 212 EVO http://www.newegg.com/Product/Product.aspx?Item=N82E16835103099 . It is really one of the best air CPU coolers out right now. Newegg has it for about $39. I have not used the GammaXX 300 so I can't really say for sure how it will perform under a overclock at full load but the Hper 212 EVO I have used and it works great.
Personalty I would get the COOLER MASTER Hyper 212 EVO http://www.newegg.com/Product/Product.aspx?Item=N82E16835103099 . It is really one of the best air CPU coolers out right now. Newegg has it for about $39. I have not used the GammaXX 300 so I can't really say for sure how it will perform under a overclock at full load but the Hper 212 EVO I have used and it works great.