A cooling system includes one or more heat generating components located within an enclosure. A first conduit is thermally connected to one or more of the heat generating components, and the first conduit is fluidly connected to a distribution manifold and a condensing unit. The condensing unit is located external to the enclosure and above the heat generating components. The distribuition manifold is located below the heat generating components. A second conduit is fluidly connected to the condensing unit and the distribution manifold. The cooling system includes a two-phase cooling medium. The first conduit, condensing unit, second conduit and distribution manifold form a loop in which the cooling medium circulates.