A motherboard includes a power circuit, a system power supply, and a central processor unit (CPU). The power circuit includes a direct current (DC) voltage input terminal. A first control circuit receives a direct current (DC) voltage through the DC voltage input terminal and outputs a first control signal. A second control circuit receives the first control signal and outputs a second control signal to the CPU and output a third control signal. A switching circuit includes a number of switches. The second control signal controls the corresponding switches to be on or off. A voltage converting circuit receives the third control signal and converts the DC voltage from the DC voltage input terminal, and outputs the converted DC voltage to the system power supply. The CPU receives the second control signal and controls the motherboard operation.