How to beat the heat generated by computer processors

Paul Boughton

The side effects of increasing performance demands on modern processors include higher power consumption and emission. Both have a great impact on the issue of waste heat and ventilation.
A complicating factor, when looking at the problem of waste heat, is the comparatively small size of processors. Consider the following example:
A light bulb with the power of 25watts has a surface of roughly 100cm≤, that makes 0.25W/cm≤. The Pentium III processor, for instance, has a surface of only 2cm≤, but a power density of 12.5W/cm≤, or 50 times the amount of heat of a light bulb per surface unit.
With the goal of maximising performance without increasing power consumption and emission, the latest Pentium M processors have gone some of the way to reduce power emission, even in frequency ranges of more than one GHz.
Still, all this heat must be carried away from the chip as effectively as possible. Otherwise, the temperature of the processor will rise, as well as that of the surrounding electronics. If certain temperature limits are exceeded, the electronic equipment will malfunction and the components can be irreparably damaged. In order to maintain an acceptable temperature around the processor, the dissipation of the lost heat can only be managed by releasing the heat into the surrounding air. This means that given a higher ambient temperature, more effort must be placed on cooling the electronics.
The problem of high power density inevitably led to the idea of making the surface of the heat-radiating source larger. The heat sink enlarges the surface area many times over, allowing the waste heat to dissipate sufficiently. For these heat sinks to function properly, it is necessary for the surrounding air to flow through them.


SMA Technologie AG is based in Niestetal, Germany. www.SMA.de

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