What Is a Motherboard? A Basic Definition

Motherboard diagramMotherboard diagram

1. CPU socket
2. Chipset3. DIMM/RAM slots
4. PCIe x16 slot5. PCI x1 slot6. M.2 connector
7. SATA ports8. Front panel connectors9. USB 2. header
10. USB 3.1 Gen1 header11. USB 3.1 Gen2 header12. ATX power connector
13. CPU power connector14. BIOS chips15. CMOS battery
16. Fan headers17. Front panel header18. VRM heatsink
19. COM/Serial header20. TPM header21. RGB header

The motherboard is where a PC’s CPU, input/output (I/O) and memory connectors live. Above you’ll find a diagram of a typical motherboard and its corresponding parts.

Note that motherboards vary in appearance and available ports and connectors, and things like fan headers, M.2 connectors and the BIOS battery are found in different places depending on your motherboard.

Most motherboards come in one of three sizes:

  • ATX - Measures 12 x 9.625 inches. This is the standard and biggest. As such, it’s the best choice for features and expansion.
  • Micro-ATX - Measures 9.625 x 9.625 inches.
  • Mini-ITX - Measures 6.75 x 6.75 inches. The smallest option. Used in compact PCs.

This article is part of the Tom's Hardware Glossary.

Further reading:

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