A heat dissipating device for a CPU includes a chassis (10), a heat sink (20), a fan cover (50) and a fan (60). The heat sink includes a coin-shaped connecting piece (22) and a plurality of cooling fins (30) arranged radially and defining an inter space for receiving the connecting piece. A plurality of airflow passages is formed between adjacent cooling fins. A plurality of heat pipes (40) is attached to a periphery of the cooling fins and the chassis. The fan cover partially surrounds the heat sink. The fan is secured to the fan cover to provide forced airflow through the airflow passages of the cooling fins radially.