Bitbender Forums has posted an article on changing Fan speeds

We all know that we need fans, as our computers would self-destruct without them. CPU manufacturers are shrinking die sizes and cutting core power. This makes a cooler running CPU. But, they are also increasing speed, which increases temperature. As the main power dissipated is caused by dynamic switching current. CPU's are approaching W/cm temperatures that are rivaling space vehicle re-entry (paraphrased from an article by Kaveh Azar, Ph.D in 'Electronics Cooling'1). The thermal limits may yet put an end to Moore's Law. The DC Brushless Fan is the best solution for now, but some predictions are that computers will soon be at 70dBA or the same noise level of freeway traffic. In the future we all may be liquid cooling but the heat has to go somewhere.

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