The first type adaptor cable assembly has an inner connector equipped with a plug board derived from the FP5 for mating with the FP5 vertical receptacle connector, and an outer connector configured to be in compliance with the FP5 or QSFP-DD receptacle connector and disposed at a rear end of the cage for mating with the FP5 or QSFP-DD inserted into the cage. Notably, the connection between the inserted FP5 and QSFP-DD and the corresponding FP5 or QSFP-DD receptacle connector directly attached/linked to the adaptor cable, is same with the traditional connection between the inserted FP5 or QSFP-DD and the corresponding receptacle connector which is only mounted to the main/external printed circuit board without directly attachment to the cable.