A heat dissipating method is applied to a computer system having a timing signaling mechanism and a temperature sensing unit. Firstly, a process of setting a dissipating temperature operating mode is performed. Then, a periodic signal is regularly transmitted to a basic input output system by the timing signaling mechanism of the computer system, and a temperature of each of hardware devices is regularly sensed by the temperature sensing unit. Subsequently, a heat dissipating unit of each of the hardware devices is actuated to perform a heat dissipation process according to the temperature sensed by the temperature sensing unit and the dissipating temperature operating mode. Therefore, the present invention can control operating intensity of the heat dissipating units and achieve hardware monitoring without requiring additional software or hardware, such that heat dissipating and operation efficiencies of the hardware devices of the computer system can be improved.