A heat dissipating apparatus includes a retention module (20) forming clipping portions (26) thereon, a heat sink (10) mounted to the retention module, and a clip (30) engaged with the retention module and the heat sink. The clip includes a resilient clipping member (32) clasped with the clipping portions, and an operating member (34) pivotally mounted to the clipping member. The operating member includes a longitudinal pole (340) rotating about an axis thereof. The longitudinal pole forms a supporting portion (341) to support the clipping member away from the retention module in the process of its rotation from unlock to lock position. At the lock position, the clipping member securely engages with the clipping portions of the retention module, and the heat sink is downwardly pressed by the longitudinal pole to have an intimate contact with a heat generating component (8).