The socket system comprises a set of vertically-stackable sockets. A first socket mounts on a printed circuit board to receive a first chip module, and a second socket stacks on the first socket to receive a second chip module. The first socket includes a first set of embedded contacts to electrically connect the first chip module to the printed circuit board, and a second set of embedded contacts to electrically connect the second socket to the printed circuit board. The second socket includes a third set of embedded contacts to electrically connect the second chip module to the printed circuit board. System upgrades are enabled by replacing the chip modules.