A power supply with heat sink is mounted inside a computer, and includes a support, a circuit board arranged on a surface of the support, and a heat sink provided on another surface of the support. The support defines a slot substantially therein. A plurality of electronic components and a plurality of thermal components are respectively provided on opposite surfaces of the circuit board. The thermal components are evenly attached to the heat sink. The heat sink conducts and dissipates heat generated by the thermal components, thereby reducing noise and cooling large area. The power supply with heat sink is assembled flexibly for saving space.