PICMG is a specification that defines a CPU form factor and corresponding backplane connectors. This standard moves components typically located on the motherboard (i.e. memory, CPUs and chipset components) to a single plug-in card. The “motherboard” is replaced with a simple “passive backplane” that provides ISA, PCI and PCIe connectors. The backplane connections also include a dedicated PICMG system slot for the CPU card.

The backplane design is simple and robust, with a very low likelihood of failure, given its passive nature. This allows a much lower Mean Time to Repair than classic computer motherboard approaches, as electronics associated with CPUs can be replaced without having to remove peripheral devices.

PICMG 1.0 CPU cards look much like a standard ISA card with extra gold finger connections for the PCI bus.

PICMG 1.3 is commonly referred to as SHB Express and is a modernization of the PICMG 1.0 single-board computer specification. SHB Express uses the same physical form factor as PICMG 1.0 boards with the additional feature of PCI Express slots instead of the outdated ISA slots.