Abstract: A computer system including a chassis, a plurality of motherboards, a fan control module and a plurality of fans is provided. A plurality of motherboard position signal generating units is disposed in the chassis. Each of the motherboards includes a signal generating circuit and a board management controller. The signal generating circuit coordinates with one of the motherboard position signal generating units to generate a motherboard position signal. The board management controller receives the motherboard position signal and a motherboard working temperature signal to output a motherboard working state signal. The fan control module coupled to the board management controller of each of the motherboards receives the motherboard working state signals and generates a plurality of fan control signals accordingly. The fans coupled to the fan control module determine operation according the fan control signals.