Abstract: The chassis for an electronic assembly includes a plurality of cooling bars which are mounted parallel to each other and spaced apart to receive electronic assembly modules. The cooling bars have internal passages for the flow of coolant, and the bars have a plurality of slots formed in the sides thereof facing adjacent cooling bars. The electronic assembly module in the preferred embodiment comprise a pair of circuit board assemblies with a heat conducting plate sandwiched therebetween, and extending slightly beyond the margins of the circuit boards to form heat conducting flanges along opposing sides of the module. The circuit modules are positioned between adjacent cooling bars with the heat conducting flanges fitting in the slots of the cooling bars. Clamping means force the heat conducting flanges into intimate thermal contact with the slots of the cooling bars. In a preferred embodiment, the clamping means comprises a plurality of wedge blocks which are cammed into the flanges.