A circuit board assembly for installation in a cabinet includes a first standards based size first mounting frame portion having a PCB mounted thereto. A second mounting frame portion is connected to the first mounting frame portion having no portion of the PCB connected thereto. A combination size of the first and second mounting frames defines a larger second standards based size. Multiple heat transfer components may be connected to the first or second mounting frame portion provide a conduction/convection cooling path. The first mounting frame portion may include a first false board edge and the second mounting frame portion includes one or more false board edge(s) positioned laterally and oppositely directed to the first false board edge. The first and second false board edges are slidably received in opposed slots created in a cabinet.