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November 30, 2000
Summary
Proper cooling is one of the most crucial features with respect to reliable operation of any PC. Overclocking stresses the need for adequate cooling even further. The relatively low premium to be paid for a good cooling device is in no relation to the gain that can be achieved, both with regard to reliability and logevity of the components as well as to unlock the maximum performance of the system via overclocking. Some theoretical background as well as fantasy and minor skills with hacksaw and file are no prerequisite but come in handy to mount a massive combo on a clearance restricted mainboard. Cooling the CPU is the best known application for heatsink/fa combos but smaller units are available to also cool chipset and graphics engines. Small pieces of recycled heatsink can be used to cool an often overlooked but nonetheless very hot part: the clock generator. Altogether, a $20 investment can greatly increase the health and performance of any system.
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Everyone who is interested in cooling is familiar with the latest additions to the cooling world: circular coolers. Thermaltake have built themselves a reputation for supplying those round heat sinks with fans integrated instead of sitting on top, so have some other companies. What appears to be counterintuitive at first glance, (aren’t all CPUs squares or rectangular) does have some real world physics behind its principle. That is, the principle of any efficient cooling is to move the heat away from its source as quickly and efficiently as possible.
Some two and 1/2 years ago, California Graphics showed what could be achieved with intelligent cooling of graphics cards. A variety of measurements taken by Shiloh Jennings (Hardware.pairnet) revealed the interesting fact that the temperatures in the center contact area with the chips were actually lower than those measured at the fins used for heat dissipation. In a short interview, Greg Moeller, designer of the miracle heat sinks briefly explained to me the underlying design considerations:
- Heat absorption and cooling capabilities are influenced by heat capacitance and conductivity.
- Capacitance is the product of the materials capacitance constant and the mass used.
- If the mass in the area of contact is kept to a minimum whereas more mass is accumulated in the fins, the latter will act like a sponge for excess heat.
- Adequate airflow around these fins will allow for heat dissipation. The shape of the fins is important since it determines surface velocity and aids in preventing turbulences.
- The possibly best shape for fins is an elongated drop shape that, similar to an airplane’s wing, provides high surface velocity with good laminar flow and little turbulences.
- Aside from good cooling, a "wing-shape" also greately reduces noise.
According to all these specifications, the best heatsink would be one that provides radial airflow over an empty center with drop-shaped fins flanking the surround. Needless to say that a circular design offers the advantage of providing equidistant positioning of the individual fins around the center. Further, ideally, the fan should be placed in the center of the heat sink itself.
Time to head over to the next hardware store
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