Abstract: A heat dissipation device includes a fin set, a cover, a first fan, a second fan and a control module. The fin set includes a plurality of cooling fins transversely spaced apart and has a substantially flat section at a bottom thereof for contacting a heat source. The cover includes a plate which covers a top surface of the fin set and has two inlets longitudinally spaced apart. The first and second fans are mounted in the two inlets of the cover for generating airflow toward front and rear top sections of the fin set respectively. Additionally, the control module is configured to either actuate the first and second fans upon receiving a working signal or execute the following steps upon receiving a dust-disposal signal: (a). turning on the first cooling fan and turn off the second cooling fan simultaneously for a period of time; and (b). turning on the second cooling fan and turn off the first cooling fan simultaneously for a period of time.

Abstract: Fan speed control methods are provided to dissipate heat from an electric device in a computer system. A load-temperature curve of the electronic device is determined by detecting load and temperature thereof within a working interval. Subsequently, a fan speed-temperature curve is determined according to the load-temperature curve, and the fan speed is controlled according to the fan speed-temperature curve.