A method and an apparatus for cooling, preferably within an enclosure, a diversity of heat-generating components, with at least some of the components having high-power densities and others having low-power densities. Heat generated by the essentially relatively few high-power-density components, such as microprocessor chips for example, is removed by direct liquid cooling, whereas heat generated by the more numerous low-power or low-watt-density components, such as memory chips for example, is removed by liquid-assisted air cooling in the form of a closed loop comprising a plurality of heating and cooling zones that alternate along the air path.