A system comprising: a plurality of circuit board modules (100, 100', 100"), wherein each circuit board module includes: a primary cover including a plurality of fins or channels for guiding cooling air flowing on surface of the primary cover; a secondary cover ; a gasket seal provided along a perimeter of the primary cover; a circuit board sandwiched between the primary cover and the secondary cover, wherein the primary cover and the secondary cover couple to form a sealed casing enclosing the circuit board; a backplane , wherein the plurality of circuit board modules are coupled to the backplane; and a backplane cover plate coupled to the backplane, wherein the backplane cover plate is provided between the backplane and the plurality of modules coupled to the backplane, wherein a plurality of fins or channels are provided on a surface of the primary cover of a second circuit board module , wherein the plurality of fins or channels of the primary cover guide the cooling air flowing on the surface of the primary cover , wherein an air gap is provided between fins or channels of the secondary cover of a first circuit board module of the plurality of circuit board modules (100, 100', 100") and said fins or channels of the primary cover of the second circuit board module of the plurality of circuit board modules, wherein the second circuit board module is adjacent to the first circuit board module , wherein the fins or channels of the secondary cover of the first circuit board module and the fins or channels of the primary cover of the adjacent second circuit board module are provided opposite from each other, and wherein the air gap is 0,254 mm to 1,270 mm wide. a primary cover including a plurality of fins or channels for guiding cooling air flowing on surface of the primary cover; a secondary cover ; a gasket seal provided along a perimeter of the primary cover; a circuit board sandwiched between the primary cover and the secondary cover, wherein the primary cover and the secondary cover couple to form a sealed casing enclosing the circuit board; a backplane , wherein the plurality of circuit board modules are coupled to the backplane; and a backplane cover plate coupled to the backplane, wherein the backplane cover plate is provided between the backplane and the plurality of modules coupled to the backplane, wherein a plurality of fins or channels are provided on a surface of the primary cover of a second circuit board module , wherein the plurality of fins or channels of the primary cover guide the cooling air flowing on the surface of the primary cover , wherein an air gap is provided between fins or channels of the secondary cover of a first circuit board module of the plurality of circuit board modules (100, 100', 100") and said fins or channels of the primary cover of the second circuit board module of the plurality of circuit board modules, wherein the second circuit board module is adjacent to the first circuit board module , wherein the fins or channels of the secondary cover of the first circuit board module and the fins or channels of the primary cover of the adjacent second circuit board module are provided opposite from each other, and wherein the air gap is 0,254 mm to 1,270 mm wide. <EOS>