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July 7, 2003 by Mike Chin
Thermally-controlled CPU coolers are more common than ever before. It's a simple concept: Tie the speed of the fan to the temperature of the CPU. The hotter the CPU gets, the faster the fan spins. The benefit is reduced noise without sacrificing cooling. You may already know that Intel's stock P4 coolers use thermal fan speed control (see the sidebar "Intel thermal control fan: At what temp?"), though it is not really used to keep the fan quiet.
In theory, thermally-controlled CPU coolers sound really good, but in practise, details such as the noise quality of the fan at low speeds, the temperature vs. fan speed curve, the location of the fan speed thermistor, and the quality and design of the heatsink itself all have to come together to make a cooler that performs well quietly.
Arctic Cooling's Super Silent Pro TC heatsink fan for socket-A (AMD) was reviewed in SPCR's first article on thermally-controlled coolers. The Arctic Cooling Super Silent 4 Pro TC for Pentirum 4-478 socket CPUs bears a strong family resemblance to that earlier product. The Super Silent 4 Pro TC is a brand new product that is not featured yet on the Arctic Cooling web site at time of writing. It is their second generation temperature controlled cooler for P4-478.
For the record, the obligatory product packaging shot:
It is a cardboard box just slightly larger than the HSF, containing the HSF, a small tube of silicone heatsink compound (said to contain 30% metal oxide), and a brief note explaining that
"At low temperatures the fan runs either not continuously or very slowly. For the CPU this is not a problem at all, since the cold heatsink even without a fan running is sufficient to keep it cool."
They must have received complaints of alarm for this note to be included.
||Intel Pentium 4 up to 3.06 GHz; Intel Celeron up to 3.06 GHz
|Heat Sink Dimensions
||94 (l) x 76 (w) x 40 (h) mm
||80 (l) x 80 (w) x 73 (h) mm
||97 (l) x 115(w) x 78 (h) mm
||1400 - 2800 RPM
||14 - 36 CFM
||12 - 23 dB
||0.18° C / W
One attribute not covered by the specs is weight, which is around 450 grams.
A clearly visible difference (compared to their last gen SS4TC) is the design of the fan. The frame around the blades has been reduced to a minmum, and the bearing housing is unusually tall. As other designs such as the Zalman 7000 have shown, minimizing the fan frame can reduce turbulence losses in airflow and improve cooling. It can also reduce noise.
The fan, its interface to the heatsink, and the mounting clips for the HSF are all integrated neatly into a one-piece mostly plastic assembly. It is clipped tightly to the heatsink via 4 plastic tabs that catch on a lip on the outermost fins. there are also 4 resilient pads between the top of the HS fins and the plastic fan / clip assembly. These are said to provide noise / vibration reduction, but the improvement can only be marginal because the HSF assembly is clamped tightly together when installed on a CPU.
The basic heatsink itself is a chunky block of aluminum with a thick base and 28 fins. It is a bit larger than the standard Intel P4 HS, and about 20% taller as well. The base is flat well finished but has visible lines that can be felt with the fingernails. (It is, however, difficult to capture in a low-pixel image.) Lapping would probably improve performance.
A thermistor at the end of a short pair of leads is wedged in the center of the fins as shown above. The same arrangement was used in Arctric Cooling's earlier socket-A HS.
Also visible in the above photo are the mounting clips. The two visible clips are hinged hooks at the end of an encapsulated steel tension spring, probably like those used on conventional socket-A / 370 heatsinks. There are two such tension springs for the 4 hooks. Large plastic handled finger tabs make mounting and removing the HSF a cinch: Place the HS atop the CPU, hinge a clip outwards while pressing down, then hinge the clip back to engage the square hole in the retention frame. Engaging clips on opposite corners seemed to be the most expedient method.
Another nice detail is the 3-pin fan lead with RPM monitoring, which is protected by a tidy webbing sleeve. It is 8" (20 cm) long: not so long to be a bother and long enough to reach the appropriate 3-pin header on any motherboard. Well thought out. The fan blows down on the HS, by the way.
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