"The Akasa AK-961 heatsink is designed for socket 775 Intel
Pentium 4/D and Core 2 Duo processors. The AK-961 heatsink's fan spins at speeds
of 500-3400RPM, which is slightly more than the AK-960E can muster.
Also, the fan on the AK-961 is internally illuminated with blue LEDs and the motor is suspended from the frame; an open fan frame style which yields quieter operation and better airflow at really low impeller speeds. Akasa's AK-961 heatsink is made from a collection of
very thin stacked aluminum fins with zippered interlocking tabs, three copper
heatpipes, and a small block of copper at the base."