Zalman ZM-F3's are very very good. They perform on par with Gentle Typhoon's (actually slightly better
), and they undervolt beautifully (with the 7v resistor cables provided). Not to mention you can get four ZM-F3's for the price of a single Gentle Typhoon.
Why people keep promoting these Gentle Typhoons is beyond me - overpriced with a high-pitched whine - people can do better for cheaper.
ZM-F4's look even better