An apparatus for providing forced flow cooling in a circuit card environment, the apparatus comprising: at least one circuit card including first and second longitudinally spaced circuit card subassemblies (104, 106), connected together into a single circuit card oriented substantially in a lateral-longitudinal plane, the first and second circuit card subassemblies (104, 106) being connected together by a laterally extending card connector oriented in a parallel lateral-longitudinal plane to the first and second circuit card subassemblies (104, 106), the first and second circuit card subassemblies (104, 106) having first and second operating temperatures, respectively, the first and second operating temperatures being different from one another; the apparatus being characterised by a housing defining a housing internal volume which completely three-dimensionally surrounds the circuit card; a first temperature inlet coupling for routing a first temperature-control fluid into the housing, the first temperature inlet coupling being laterally aligned with the first circuit card subassembly; a first temperature outlet coupling for routing the first temperature-control fluid out of the housing, the first temperature outlet coupling being laterally aligned with the first circuit card subassembly and longitudinally spaced upon the housing from the first temperature inlet coupling; a second temperature inlet coupling for routing a second temperature-control fluid into the housing, the second temperature inlet coupling being laterally aligned with the second circuit card subassembly; a second temperature outlet coupling for routing the second temperature-control fluid out of the housing, the second temperature outlet coupling being laterally aligned with the second circuit card subassembly and longitudinally spaced upon the housing from the second temperature inlet coupling; wherein the first temperature-control fluid is directed laterally across at least a portion of the first circuit card subassembly within the housing internal volume in a first flow path to induce the first operating temperature concurrently with the second temperature-control fluid being directed laterally across at least a portion of the second circuit card subassembly within the housing internal volume in a second flow path to induce the second operating temperature. at least one circuit card including first and second longitudinally spaced circuit card subassemblies (104, 106), connected together into a single circuit card oriented substantially in a lateral-longitudinal plane, the first and second circuit card subassemblies (104, 106) being connected together by a laterally extending card connector oriented in a parallel lateral-longitudinal plane to the first and second circuit card subassemblies (104, 106), the first and second circuit card subassemblies (104, 106) having first and second operating temperatures, respectively, the first and second operating temperatures being different from one another; the apparatus being characterised by a housing defining a housing internal volume which completely three-dimensionally surrounds the circuit card; a first temperature inlet coupling for routing a first temperature-control fluid into the housing, the first temperature inlet coupling being laterally aligned with the first circuit card subassembly; a first temperature outlet coupling for routing the first temperature-control fluid out of the housing, the first temperature outlet coupling being laterally aligned with the first circuit card subassembly and longitudinally spaced upon the housing from the first temperature inlet coupling; a second temperature inlet coupling for routing a second temperature-control fluid into the housing, the second temperature inlet coupling being laterally aligned with the second circuit card subassembly; a second temperature outlet coupling for routing the second temperature-control fluid out of the housing, the second temperature outlet coupling being laterally aligned with the second circuit card subassembly and longitudinally spaced upon the housing from the second temperature inlet coupling; wherein the first temperature-control fluid is directed laterally across at least a portion of the first circuit card subassembly within the housing internal volume in a first flow path to induce the first operating temperature concurrently with the second temperature-control fluid being directed laterally across at least a portion of the second circuit card subassembly within the housing internal volume in a second flow path to induce the second operating temperature.