Abstract: An adjustable fastening device for integrated circuit chips of varying thicknesses includes a radiating fin, a base plate, a number of resilient cramps and a number of screws. The radiating fin has at least two opposite sides which each include an upper ledge, a lower ledge and a longitudinal recess therebetween. Each upper ledge defines at least one vertical through-hole. Each lower ledge defines at least one recess corresponding to the vertical through-hole. The base has at least two opposite sides from each of which a hook downwardly extends. The cramps corresponding to the hooks have a top portion, a side portion and an arcuate portion extending therebetween. The top portion defines a hole to engagingly receive one of the screws. The side portion defines a slot configured to receive a corresponding hook. An integrated circuit chip is received between the radiating fin and the base.