One of the best out there is the Thermalright XP-120. I just installed one for a friend on his AMD 64 3800 and he is getting idle temps of 36C with fairly warm room temps. I have the XP-90 version because the XP-120 does not fit well on my motherboard. Read some reviews and you will see that the XP-120 is at the top in temperature while being one of the quietest heatsinks out there. You can use a very low rpm 120mm fan that will blow around 85cfm at only 35dB. It is also about half the weight of the other high performance heatsinks so stress on your chip and motherboard is minimized. My XP-90 is also very good. I run it on a AMD 64 3200 and get 42C max temps with significant overclocking. A note on the XP-120: goto www.thermalright.com and check the motherboard compatibility list because the base is large and may hit some of the capacitors around the cpu socket. That is why I had to go with the XP-90 but I am not disappointed and it looks great. Here is a review of the XP-120.