if you mean a cpu fan, and quietness is important to you, then your best bet might be the new alpha pal8045. it takes an 80mm fan, natively which helps noise. but the fan only fits on newer amd boards, becasue of its mounting mechanism - it uses the four holes around the cpu to attach itself to the motherboard. otherwise, you might want to look into the thermalright sk-6. lotsa people here reccomend it. it take s a 60mm fan, so the sky's the limit on noise, there (almost literally - some 60mm fans sound like planes!)