Abstract: A CPU heat dissipating device includes a heat-conducting base plate adapted to be mounted on a CPU and having a flat top surface, an annular fin unit mounted on the top surface of the base plate and projecting integrally and upwardly from the entire outer periphery of the base plate, an air-drawing fan mounted on the top surface of the base plate and located inside the annular fin unit, and a guide plate fixed on the base plate and located immediately over the annular fin unit so as to cover the annular fin unit. The guide plate has an opening which is formed therethrough and located immediately over the fan, and an annular flange which projects integrally and upwardly from the base plate and which is located around and adjacent to the opening so as to guide cooling air to flow onto the top surface of the base plate in a direction perpendicular to the top surface of the base plate, thereby reducing turbulence between the base plate and the guide plate.