FrostyTech posted a review on the Zalman CNPS9500 AT Intel Core 2 Duo Heatsink

Zalman's CNPS9500 AT is identical in materials and size to previous CNPS9500-series heatsinks, but this heatsink is offered with a 4-pin PWM fan for Intel-based computer systems, rather than the standard 3-pin fan power cable. The heatsink is voluminous in size and weighs about 530grams. Like all heatsinks produced by Zalman, it's intended to operate quietly and efficiently without much noise. Because the Zalman CNPS9500 AT heatsink uses a Pulse Width Modulation fan, no FanMate2 fan speed controller is included with it - it's just not needed.

Zalman CNPS9500 AT Intel Core 2 Duo Heatsink Review