Power supply for server

PURPOSE: A power supply for a server is provided to improve the efficiency of a server power supply unit by increasing the operation frequency of a switching terminal. CONSTITUTION: A PFC(Power Factor Correction) unit(11) is connected to an input power source in order to satisfy a harmonics regulation. A DC / DC unit(122) comprises at least one switching device. The DC/DC unit is comprised of a switching unit for switching a link capacitor voltage with a predetermined operation frequency and the DC/DC unit. A DC/DC controller(13) is connected to the switching unit to control the DC/DC unit. A frequency variable circuit(14) detects the output current of the link capacitor to obtain load information.