A system for testing a motherboard performance includes a control device, a voltage processing circuit, a voltage regulating circuit and a voltage feedback circuit. The control device stores a plurality of predetermined voltage values and outputs control signals according to the plurality of predetermined voltage values. The voltage processing circuit receives the control signal and outputs a plurality of PWM signals according to the control signal. The voltage regulating circuit receives the plurality of PWM signal and outputs a plurality of DC voltage to a plurality of voltage input terminals of the motherboard. The voltage feedback circuit collects voltage signals at the plurality of voltage input terminals of the motherboard.