a multi - channel module with a plurality of chips is mounted on a multilayer circuit board and has a simple and highly reliable structure cooling system for cooling the heat generated by the chips consuming a large amount of electric power . the cooling system uses in the horizontal direction a coolant supply pipe having straight tube sections and flexible bellows sections alternately disposed in the axial direction of the pipe . the straight tube sections of the aforesaid coolant supply pipe are brought into contact with the upper faces of the chips by a spring force so as to cool continuously the plurality of chips with the coolant flowing in one coolant supply pipe thereby providing a simply structured cooling system for chips . such a structured cooling system enables the collective assembly of cooling parts for a plurality of chips with only a small number of parts and produces highly reliable effects thereby being able to implement the miniaturization of a main frame computer .