A cooling host module is operable for providing cooling gas flow in a substantially isolated closed loop for a computing device. The computing device comprises a substantially vertical first face having an inlet portion comprising no more than about a lower third of a height of the first face for inlet gas flow and a substantially vertical second face opposite the first face for outlet gas flow. The cooling host module comprises: a heat exchanger adjacent to the second face of the computing device for cooling outlet gas flow; a gas flow path directing air exiting the heat exchanger beneath the computing unit; a gas moving device for moving gas in the gas flow path; and a vent towards distal end of the gas flow path for providing gas flow to the inlet portion of the first face of the computing device.