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Anatomy of a Computer Motherboard

by Paul Sanders


Your computer's motherboard is the heart of your system, and if you're building a custom computer or upgrading any part of it, you'll need to know how the motherboard works. Once you understand the basic motherboard features, you'll be more prepared to shop for one also to find computer components that are compatible with it.

Motherboard Parts Explained:

  1. Chipset: The motherboard's chipset handles communication between the microprocessor, or CPU, and other parts of your computer. It's usually designed for use with a specific family of computer processors, so you'll often see motherboards and CPUs sold together. The actual term "chipset" refers to two chips in the motherboard itself, known as the northbridge and the southbridge.

    Chipset Functions

    • Northbridge: The northbridge connects the CPU to high-speed components like RAM and graphics card slots.

    • Southbridge: The southbridge connects to slower peripheral devices like the Flash ROM (explained below) and PCI expansion slots.

  2. CPU slot: Every motherboard has a slot, or socket, that is compatible with a certain type of computer processor. The socket type and the motherboard chipset must match the processor type and speed for the two to work together.

  3. Bus: A bus is a connection on the motherboard that carries data between the various parts of the motherboard, such as the CPU and RAM or the northbridge and southbridge. Different types of buses, like parallel and serial buses, transfer data in varying ways and at different speeds. The performance quality of your computer increases with the speed of the bus; the faster the bus, the more performance you get from the computer.

  4. Memory slots: All desktop motherboards have built-in slots for PC memory modules, which the CPU uses to perform calculations. The number of memory slots, and the type of random access memory (RAM) they accept, varies from one motherboard to the next.

  5. Expansion slots: Your motherboard may include one or more expansion slots of varying types for connecting expansion cards, such as a video graphics card or a sound card. Each slot has an interface type that determines what shape and type of card it can accept. The most common expansion slot type for current motherboards is PCI-Express, but you'll also find PCI and AGP slots on many older motherboards.

  6. Flash ROM: Most motherboards contain a flash memory chip to store the firmware or BIOS, which is used to help boot the computer when it starts. The contents of this type of memory persist even while the computer is off, though it can be rewritten if needed.

  7. Power connectors: Some devices, like disc drives and graphics cards, will require additional power from the motherboard, so most boards will include power connectors for supplying that power. The motherboard, in turn, gets its power from the main computer's power supply.

  8. Integrated graphics and sound controllers: Computers without separate graphics or sound cards, which includes most computers, often use an integrated chip and the computer's RAM to provide 3D rendering and audio for computer programs. Motherboards labeled with "integrated graphics" include these types of chips.

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