A heat sink includes a base (10) and heat pipes (20). The base includes a bottom surface contacting with a heat-generating electronic component (100), an upper surface defining grooves (12) receiving the heat pipes therein. Evaporating sections (22) of the heat pipes are located near a first end portion (10a) and condensing sections (24) of the heat pipes are located near a second end portion (10b) of the base. A first fin assembly (30) is mounted on the upper surface and a second fin assembly (40) is mounted on the bottom surface of the base near the second end portion thereof. A fan (200) is located near the second end portion of the base.