well i just bought the Cool it liquid cooling system for my pc for 180 its great. Everything is already put together but i f you dont have that much this is a good air cooled heat sink with artic silver 5 thermal paste
http://www.newegg.com/Product/Produc...82E16835118020
should keep you temps low, i have already owned this i like how it handle my temps and also it looks cool in the case if you have a side window. Very quite
You can do some decent over clocking with this heat sink