Computer radiating apparatus

The device comprises a power supply testing unit connected to at least one fan controller on the main board, a time controller connected to the power testing unit, a voltage control unit connected tothe time controller and the secondary power supply on the main board, a power switching unit connected to the fan controller, the time controller and the voltage control unit. When the time controller is in stop state, the power switch unit is connected to the fan controller and the first state of the fan. When the time controller is in active state. The power switch unit is connected to the voltage control unit and the second state of the fan. When computer is shut down, the power for heat dispersion fan is still supplied, in order to lower temperature of host computer and CPU so as to prolong service life of the computer.