A heat sink includes first and second base plates to contact with first and second surfaces of a heat source, respectively. The first base plate includes a support unit protruding from a first surface and a first dissipating unit to dissipate heat from the heat source. The second base plate includes a penetrating hole spaced apart from an edge portion to hold the support unit and a second dissipating unit to dissipate the heat from the heat source. A coupling member is positioned on an upper surface of the support unit and applies a force to the first and second base plates to thereby combine the first and second base plates to the heat source. The base plates are combined to the memory module without any loss of the surface area of the dissipating fin, to thereby improve the dissipation efficiency of the heat sink.