A cooling-fan-free system module includes a housing unit, a circuit module, and a heat radiating unit. The housing unit includes a front and a rear case assembled together to define a receiving space therebetween, and the rear case is made of a highly heat conducting metal material. The circuit module is received in the receiving space of the housing unit, and includes a circuit board, and at least one heat-producing element mounted on and electrically connected to the circuit board. The heat radiating unit includes at least one insulating heat conductor bonded to an inner side of the rear case corresponding to the heat-producing element for transferring the heat produced by the heat-producing element to the rear case, and at least one heat radiating member integrally formed on a back side of the rear case and consisting of a plurality of radiating fins.