Abstract: An electronic circuit board assembly and method that enable close stacking and cooling of closely positioned pluralities of similar electronic I/O or memory boards and requiring high speed communication between the boards, such as high speed switching amongst the I/O terminals of the boards or CPU processing, and having an upper and a lower set of similar spaced groups of closely spaced vertical boards; powering terminals aligned along the upper edges of the upper set of boards, and along the lower edges of the lower set of boards, and terminals for connection with a switching fabric disposed along the lower edges of the upper set of boards and the upper edges of the lower set of boards; power backing planes mounted to power and support the lateral edges of the respective sets of groups of boards and extending across the upper and lower sections of the frame; and a plurality of parallel closely spaced vertical switching fabric boards comprising switching fabric (or CPU processing boards) and centrally mounted