Zalman CNPS9900DF Dual Fan Flower Heatsink

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The Zalman CNPS9900DF sports an all copper construction consisting of a base 3 x 6 mm thick heatpipes and a multitude of very thin fins, all nickel-plated. By our measurements, the heatsink is 152 mm tall (6.0 inches) and approximately 870 grams (1.9 lb). By modern standards its size is rather conservative.

The core design of the 9900 series remains, though it's split into two sections each with its own fan. The fins are arranged radially, tightly packed at the center and looser at the edges while the fans disperse the air in every direction.

The DF isn't much different from the CNPS9900 MAX, The intake portion of the heatsink has been enlarged to encapsulate a second fan but otherwise it looks mostly the same. Our biggest complaint, the fan being mounted on a pair of metal stilts prone to vibration, remains. There's too much separation behind the center fan and without a casing, it doesn't generate much static pressure.

The thin fan support is freestanding, not anchored to any portion of the heatsink, making it prone to vibration.

The heatsink extends around the edges of the front 120 mm fan while the sides of the center 140 mm fan are unimpeded.

Though it looks like a six heatpipe cooler, it actually only has three. Each heatpipe is very long, wrapping all the way around the heatsink. In the image above you can see both the thick and thin ends of two of the heatpipes.

The base is a very nice mirror polish but the shape is actually more important for thermal transfer. The 9900DF's base is slightly concave; heatsinks with flat and convex surfaces perform better on the vast majoriity of heatsinks, which are usually a tiny bit concave. Two concave surfaces mating againsts each other almost guarantees a gap in the middle. The gap may be small, in the order of fractions of a millimeter, but the difference between a gap of any kind versus firm contact is easily 10°C. The screws on the bottom can be loosened so the metal mounting clips can be inserted between the base and baseplate, and then re-tightened.

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