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DESIGN DETAILS
The basic design of the CNPS9500 is a Zalman 7000 turned
sideways and perched on heatpipes. The design is a good one: Embedding the fan
inside the heatsink allows every bit of airflow from the fan blades to dissipate
heat.
The CNPS9500 is a clever evolution of the CNPS7000 design.
The diameter of the "flower" is the same as the Zalman
7000 series, and a similar 92mm fan is used. Like the 7000, the flower is
incomplete; roughly a sixth of the circumference is left open to leave room
for the heatpipes. The fins are bigger than the ones on the 7000,
so the total surface area of the fins ? and the cooling potential ?
is greater. It has the biggest cooling surface area of any Zalman HS: Zalman cites 3,698 cm2 for the 9500. The 7000 series heatsinks come in at 3,170 cm2, and the 7700 is 3,268 cm2.
The CNPS9500 turns the design sideways and elevates it above the motherboard
where there is less chance of interfering with the other components.
MODEST WEIGHT
The 9500 weighs only 530 grams, compared to 775 grams for the all-copper
7000cu or 918 grams for the 7700cu. The difference is the "tunnel" through the center of the 9500, which is devoid of any metal.
In the 7000 and 7700 series, this center forms the solid, massive base. In comparison, the base on the 9500 is a small copper plate and an aluminum top plate with the heatpipes clamped between them. Aside from the weight reduction, a second advantage of this design is that air flows
through the heatsink with little impedance. This means that all of the fin surface area can work efficiently to dissipate heat, and there is very little ineffectrive turbulence cause by sharp angle turns in airflow direction.
The center is hollow, allowing air to pass.
COOLING FOR VRMs
Unlike most "tower" style heatsinks with fans that blow
across the motherboard, airflow is not ducted from one end
of the heatsink to the other. Instead, air can escape from all sides, including
the top and bottom. This means that a substantial amount of air should end up being
blown down towards the VRMs (Voltage Regulation Modules) that usually surround
the CPU socket, cooling them in the process. This is important, as ATX motherboards
are designed with this kind of cooling in mind; many tower-style heatsinks risk
shortening the life of the motherboard because they tend to block the airflow from reaching
these components.
The fins are anchored to three heatpipes that rise gracefully
up from the base in a figure 8. The fins are attached to the middle of the
heatpipes, while both ends are attached to the base. The flow of heat inside
the heatpipes is from the ends to the middle.
Both ends of each heatpipe are attached to the base and rise up in a figure
eight.
Zalman has made excellent use of the heatpipes. The distance from a
heatpipe to the edge of a fin is never much more than a couple centimeters,
which means that there are no "dead spots" on the fins; just as the
embedded fan spreads the airflow evenly across the fins, the heat is also evenly
distributed.
INTEGRATED FAN
The fan, looking up from the bottom of the heatsink.
The LED fan is mounted on a steel bracket that positions it just above the
top of the fins. On our sample, the fan was slightly off-center. This has no
practical downside, but it suggests that the manufacturing process by which
the heatpipes are formed probably isn't quite perfect yet.
The fan blows through the heatsink, so care should be taken to install the
heatsink in the right orientation. The mounting system allows the 9500 to be installed "facing" any of four directions. Ideally, the empty side of the heatsink should face
the rear case fan, so that the hot air coming off the heatsink is immediately
exhausted.
Zalman rates the fan at 0.35A and 2600 RPM, quite high for a fan that is supposed
to be quiet. In comparison, the 92mm fan in the 7000 series is rated for 0.23A
and 2400 RPM. It is also a dual ball-bearing fan, which is usually not the best
choice for noise, although a quieter sleeve-bearing fan would not be as reliable
for use in a high-heat application like a heatsink. As with all their CPU heatsinks,
Zalman ships a Fanmate 2 fan controller with the CNPS9500, so the fan can be
easily undervolted down as low as 5V.
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