An electrical connector (100) for engaging with a complementary connector, includes an insulating housing (10) and pairs of power contacts (20) assembled in the insulating housing. The insulating housing defines a number of receiving passageways (11) extending therethrough along a front-to-back direction. The pairs of power contacts are received in corresponding receiving passageways, respectively. The insulating housing defines at least one hole (13) between two adjacent receiving passageways. The at least one hole communicates with the two adjacent receiving passageways for heat dissipation purposes.