A heat dissipation device is for use in a computer enclosure, the computer enclosure having a group of wires (20) therein. The heat dissipation device includes a heat sink assembly. A wire fixture (60) is mounted on the heat sink assembly and configured for fixing the wires thereto. The wire fixture includes a mounting plate (62) positioned on the heat sink assembly. A bridge (624) projects from the mounting plate to form a receiving room (625) below the bridge. The wires are securely bound together via the wire fixture so as not to be loosened by vibration.