Abstract: A heat sink for use in a computer for dissipating heat which includes a flat base plate having elongated coupling grooves and upright cylindircal sockets in the coupling grooves, a plurality of U-shaped radiating fins respectively mounted in the elongated coupling grooves at the flat base plate, and a slotted holding down plate covered on the flat base plate and secured to the upright cylindrical sockets at the flat base plate to hold down the radiating fins.