The invention relates to a mainboard supply circuit which comprises a first NMOS field effect tube, a second NMOS field effect tube, a first capacitor, a first inductor and a delay circuit, wherein the grid electrode of the first NMOS field effect tube is connected with a high-side gate drive output pin of a voltage regulating module; the source electrode of the first NMOS field effect tube is connected with a phase pin of the voltage regulating module, connected with a drive pin of the voltage regulating module through the first capacitor, and simultaneously connected with a memory control center through the first inductor; the drain electrode of the first NMOS field effect tube is connected with a system power supply; the grid electrode of the second NMOS field effect tube is connected with a low-side gate drive output pin of the voltage regulating module; the source electrode of the second NMOS field effect tube is grounded; and the drain electrode of the second NMOS field effect tube is connected with the source electrode of the first NMOS field effect tube and the delay circuit. The mainboard supply circuit controls the first NMOS field effect tube and the second NMOS field effect tube to be alternately conducted and the delay circuit provides a stable voltage pulse signal to supply power for the memory control center.