An exemplary power regulator circuit of motherboard includes a power connector comprising a power supply on pin, a power good pin and a first power pin for being coupled to an ATX power supply, the power good pin providing a first power good signal; an electric switch having a first terminal connected to the power supply on pin of the power connector, a second terminal connected to the power good pin of the power connector, and a grounded third terminal; a diode with the cathode connected to the power good pin of the power connector, and the anode connected to the first power pin of the power connector via a first resistor and grounded via a first capacitor; and an output terminal connected to the anode of the diode to provide a second power good signal.