Motherboard
A motherboard (also called a mainboard, system board, or logic board) is the main printed circuit board (PCB) in a computer or other electronic device. It provides the electrical connections and physical mounting points for the Central Processing Unit (CPU), Random Access Memory (RAM), expansion cards, and other critical components. The motherboard also houses the chipset, Basic Input/Output System (BIOS) or UEFI firmware, and connectors for peripherals and storage devices.
History
Early computers used backplane designs with separate cards for the CPU and memory. The first single-board motherboard for a mass‑market microcomputer appeared in the IBM Personal Computer (1981). This design consolidated key components onto one board, reducing cost and improving reliability. Over time, motherboard standards evolved: the AT form factor gave way to ATX in 1995, introducing better power management and layout. Later, smaller formats like MicroATX and Mini-ITX enabled compact systems. The integration of sound, networking, and graphics directly onto the motherboard reduced the need for separate expansion cards.
Components
A typical motherboard includes:
- CPU socket – for mounting the processor.
- Memory slots – DIMM or SODIMM slots for RAM modules.
- Chipset – manages data flow between the CPU, memory, and peripherals.
- Expansion slots – PCI Express slots for graphics cards and other add‑on cards.
- Storage connectors – SATA and M.2 slots for drives.
- I/O ports – USB, HDMI, Ethernet, audio jacks, and other external connectors.
- Power connectors – main ATX power supply connector and auxiliary CPU power.
- Firmware storage – a EEPROM or flash memory chip holding the UEFI or BIOS.
Form factors
Motherboards are manufactured in several standard sizes, known as form factors. Common ones include:
- 0 – the most widely used size in desktop computers, typically 305×244 mm.
- 0 – a smaller variant, 244×244 mm, with fewer expansion slots.
- 0 – a very compact design (170×170 mm) common in home theater PCs and small form‑factor builds.
- 0 – larger than ATX, used for high‑end workstations and servers.
Modern features
Contemporary motherboards often include built‑in Wi‑Fi and Bluetooth, multiple USB‑C ports, support for fast NVMe Solid‑State Drives, RGB LED lighting headers, and overclocking controls. The UEFI firmware has largely replaced the older BIOS, providing a graphical interface and support for larger drives. Some high‑end boards integrate Thunderbolt controllers or advanced audio codecs.