In one embodiment, a main circuit board includes a plurality of expansion slots that are operative to receive a corresponding plurality of expansion cards. The plurality of expansion slots include at least one first expansion slot configured at a first position on the main circuit board, that is operative to connect to at least one corresponding first expansion card. At least one second expansion slot configured at a second position on the main circuit board, and the second expansion slot is operative to connect to at least one corresponding second expansion card. The plurality of expansion cards includes at least one secondary expansion card that is different from the main circuit board and that is configured to be operatively coupled to at least one of the plurality of expansion slots. One or more particular expansion slots are selected for connecting one or more corresponding particular expansion cards, based on the size, dimensions, and/or function of the particular expansion cards to be connected. A programmable processor is operative to selectively regulate power supplied to particular expansion slots.