Abstract: A sealed housing for cooling a plurality of printed circuit cards includes a chassis that supports a plurality of electrical connectors retaining printed circuit cards in mutually adjacent, spatially separated relationship. A first side of a respective printed circuit card is attached to an associated convectively cooled heat exchanger, having a cooling fluid flow chamber containing thermally conductive heat exchange elements through which an internal cooling fluid flows. A sealed, forced cooling fluid recirculation structure is mounted to the chassis and recirculates cooling fluid through heat exchangers of respective printed circuit cards. The sealed, internal cooling fluid recirculation structure contains thermally conductive heat exchangers that are convectively coupled with the internal cooling fluid and are conductively coupled to a distribution of thermally conductive fins on the outside of the chassis.