An electrical connector assembly (100) made in accordance with a preferable embodiment of the present invention comprises an electrical socket (20) with a plurality of contacts received therein, an IC module (30) mounted onto the electrical socket (20) so as to make electrical connection therebetween, a heat sink assembly (40) pressing on the IC module (30) and including a heat spreader (401), and a clip (50) fastening the heat sink assembly (40) above the IC module (30). The IC module (30) comprises a substrate (301) and at least one die (302) attached on a top surface of the substrate (301). The clip (50) has a set of first fingers (504) for pressing the die (301) of the IC module (30) and a set of second fingers (505) for pressing the substrate (301) of the IC module (30).