A heat conductive member is connected to a heat-generating electronic component. A liquid tank defines a liquid injection hole. A clip assembly is connected to the liquid tank. When pressed against the clip assembly, the liquid tank is fastened by the clip assembly and retained in position. When pressed again toward the clip assembly, the liquid tank is released from the clip assembly and ejected in a direction away from the heat-generating electronic component. The liquid tank includes a tube portion and a rotation wheel. The tube portion includes a hollow tube and a positioning portion formed along a sidewall at a first end of the tube. The rotation wheel is fixed on the positioning portion and adjacent to the sidewall. The blades of the rotation wheel oppose the hollow of the tube. A second end of the tube is connected to the conduits.