A system, method, and motherboard assembly are described for interconnecting and distributing signals and power between co-planar boards that function as a single motherboard. The motherboard assembly includes a multilayered first printed circuit board having opposed parallel first and second surfaces, each having at least one land grid array (LGA) disposed thereon. The assembly further includes at least one wiring layer (Y) designed to only electrically interconnect components on or within the first PCB, and at least one wiring layer (X) designed to only electrically connect the components on the first PCB to a multilayered second PCB. The multilayered second PCB has opposed parallel first and second surfaces, the first surface having at least one LGA disposed thereon. It further includes at least one wiring layer (V) designed to only electrically interconnect components on or within the second PCB, and at least one layer (X) designed to only electrically interconnect the components on the second PCB with the components on the first PCB. A first LGA interposer couples to the LGA disposed on the first surface of the first PCB, and electrically connects at least one component to the first PCB. A second LGA interposer is sandwiched between and couples to the LGA disposed on the second surface of the first PCB and to the LGA disposed on the first surface of the second PCB. It electrically connects the first PCB to components on the second PCB.