motherboard

The motherboard, also called the mainboard or system board, is the main printed circuit board in a computer. It provides the mechanical mounting points and electrical connections that allow the central processing unit, memory, storage, and expansion cards to communicate with each other and with input/output devices. The board distributes power from the power supply through voltage regulator modules and power connectors to all components, and it routes signals via a system of buses and traces.

A processor socket accepts a central processing unit. Memory slots (DIMMs) provide volatile RAM for the CPU. The chipset controls data flow between the CPU, memory, storage, and I/O, and it often includes or is paired with a platform controller hub. Modern systems use a single chipset with integrated I/O and PCIe lanes, while older designs split tasks between a northbridge and southbridge.

Expansion slots, most commonly PCIe, allow graphics cards, network adapters, and other cards to be added. Storage interfaces include SATA and newer NVMe via M.2 or PCIe. Internal connectors carry USB, audio, front-panel power/reset, fans, and RGB lighting. The I/O panel on the rear of the motherboard exposes USB, Ethernet, audio, video, and other ports.

Motherboards come in standard form factors, with ATX, microATX, and mini-ITX being common. The form factor affects the number of expansion slots, RAM slots, and overall footprint. Compatibility depends on the CPU socket type, chipset, RAM type and speed, and BIOS/UEFI support. BIOS or UEFI firmware initializes hardware at startup and provides basic configuration options.