Patent ID: 7137015

Claim:
A switching power supply having a built-in cooling fan which functions a certain period of time after the computer system is shut down, the switching power supply including a controlling chip set mounted on a built-in printed circuit board, or mounted on a separate circuit board, the chip set including a controlling circuit having preset time or temperature, distributing a power from one of stand-by-power and other auxiliary power to the built-in cooling fan so as to power the built-in cooling fan even when the computer system is shut down till the preset time elapsed or the preset temperature reached, wherein the switching power supply being provided with a time controlling knob and a temperature controlling knob electrically connected to the chip set such that an end user adjusts the time and temperature accordingly, the knobs are arranged on a back panel of the computer for direct external access, wherein the time controlling knob and the temperature controlling knob are arranged on an interface card of the computer providing a direct external adjustment.