An electrical connector (100) for being mounted on a main PCB comprises an insulative housing (1) having a plurality of cavities (11, 12) and a rear opening (13), a plurality of insert module (3) received in the rear opening of the housing, and a shell member (21, 22) substantially surrounding the housing. Each insert module includes a plurality of contacts (31, 32) including contact portions (312, 321) extending into a corresponding cavity of the housing, and a power module (9). Each power module includes a hole (93) in a rear portion thereof. The shell member includes retaining tabs (213) in a rear portion for engaging with the openings of the power modules.