An electrical connector assembly provides an electrical connector mounted upon a main board, a CPU assembled upon connector with an interposer therebetween wherein some conductors on the CPU are electrically connected to the main board or to an external device via the conductive elements on the outer/exposed region of the interposer outside of the connector and a connection device, e.g., the connector set or the cable set, which is linked to those conductive elements on the outer/exposed region, while remaining conductors on the CPU are electrically connected to the main board via the conductive elements on the inner/hidden region of the interpose inside the connector by cooperation with the contacts of the connector.