Akasa's AK-965 heatsink utilizes three "U" shaped copper heatpipes to connect a compact copper base block with widely spaced aluminum fins. It's 95mm PWM fan spins only as fast as needed to achieve good temperature control, and works well at moving air relatively quietly through the aluminum fins. Copper heatpipes are positioned close to the processor, and in the direct path of airflow at the other end. All good thermal design criteria in fact. Now if this heatsink looks familiar to you, it's because this arrangement of copper and aluminum works, so many other companies have released similarly built heatsinks.
FULL STORY @ FROSTYTECH (http://www.frostytech.com/articleview.cfm?articleID=2137)