A heat dissipating device for cooling a heat-generating electronic device, includes a heat sink assembly (10) and a fan (20) mounted to a side of the heat sink assembly. The heat sink assembly includes a heat spreader (12), a plurality of fins (14), and heat pipes (16) thermally connecting the heat spreader and the fins. The fins include at least one fastening fin (146). The fastening fin includes a pair of mounting tabs (1462). The mounting tabs of the fastening fin are oriented towards the fan for mounting the fan on the heat sink assembly. The fastening fin functions not only for dissipating heat into a surrounding environment but also for connecting the fan to the heat sink assembly.