Components of Motherboard and their Functions

A motherboard (also called main board or system board) is a basic foundation of a computer that connects all the crucial components or parts of a system. It performs the following significant functions like:

  • Distributing power from the power supply to all hardware components.
  • Transferring of data and instructions between various hardware components.
  • Providing various sockets and pads for mounting electronic components.
  • Offering expansion slots to add other components, such as graphics card, network cards, etc.

In older desktop computers, there had very few integrated components onto the motherboard. It needs a large number of adapter cards for interfacing videos, hard disk, and floppy disk. In contrast, as the technology advanced, various interfaces have accommodated on the motherboard and fewer adapters are needed.

Nowadays, almost all the electronic components, such as CPU, RAM, expansion slots, heat sink/fan assembly, BIOS chip, etc. have integrated onto the motherboard of all personal computers (PCs). It also holds the expansion bus, Input/Output (I/O) interface, drive controllers, and system memory.

In this tutorial, we will understand different components of a computer motherboard, what they do, and where they are located on the motherboard of a computer.

Hardware Components of Computer Motherboard with Functions

A typical computer motherboard contains the following electronic components or parts that are as:

  • Chipsets
  • CPU or processor sockets or slots
  • Memory slots
  • Expansion slots
  • BIOS chip
  • CMOS battery
  • Power connectors
  • Keyboard and mouse connectors
  • Onboard disk drive connectors
  • Peripheral ports and connectors
  • Jumpers and DIP switches
  • Case fan and Heat sink

Let’s understand each component of the motherboard in brief.

Components of computer motherboard


A chipset is a set of semiconductor chips (or circuits) on the motherboard that provides interfaces for memory, expansion cards, and other peripheral devices. It is the foundation of the motherboard and made up of one or several integrated circuit chips.

It works closely with the CPU processor to collectively control the memory, buses on the motherboard, and some onboard peripheral devices. Therefore, a chipset on the motherboard must be compatible with the processor that it serves.

A chipset and socket determines what type of processor a board can support, how fast it will run, how fast buses will run, and speed, type, and amount of memory we can have. The original manufacturers such as Intel and AMD usually give the name and model number to the chipsets.

We can divide the functions of a chipset into main categories – Northbridge and Southbridge. Let’s take a brief look at both.


A Northbridge is a chipset that establishes the communication among high-speed peripherals, such as memory, PCI (Peripheral Component Interconnect) bus, AGP (Accelerated Graphics Port) bus, and the Level 2 processor cache (L2 Cache memory).

It communicates with processor and memory using FSB (Front Side Bus) that is a just set of signal pathways between the CPU and main memory. On the other hand, the backside bus is a set of signal pathways between the CPU and Level 2 cache memory, if present.

The real performance of a motherboard depends on the performance of Northbridge chipset. It also manages the communication between the Southbridge and the rest of computer.


Southbridge is a single semiconductor chipset that is responsible for controlling all onboard Input/Output functions of a computer such as USB, BIOS (FireWire), PS/2, Parallel, Series, wire-less LAN ports, IDE, audio, and so on.

It also manages the communications with the other expansion buses, such as PCI, USB, and legacy buses. The below diagram shows an example of a typical computer motherboard chipset (including both Northbridge and Southbridge) and components they interface with.

Chipset - a compnent of motherboard

Processor Sockets or Slots

The central processing unit (CPU), or simply a processor, is the brain of the computer. This electrical component performs all the mathematical calculations and 90 percent of all the functions of a computer.

There are various types of processors available for computers in the market. In today’s computers, the processor is the easiest component that we can identify on the motherboard. It is installed in either a socket or slot, depending on the type of chip.

The CPU socket or slot on the motherboard is basically flat in shape. It has several rows and columns of holes (pins) arranged in the square, as shown in the below figure.

CPU socket on the motherboard

Most of the CPU sockets have pin grid array (PGA) architecture, in which pins of the underside of the CPU processor are inserted into the socket, usually with ZIF (zero insertion force).

ZIF refers to the amount of force required to install a CPU into the socket mounted on the motherboard. It makes easy to insert and remove the processor so that the processor pins are not damaged during the insertion.

Most of the processors installed on the CPU socket are attached along with a heat sink or colling fan because they produce a lot of heat during the normal operations.

The Intel company had designed the first standard CPU socket named Socket 1, originally called “OverDrive” socket. It is usually 17 * 17 pin grid array (PGA) socket that contains 169 pins and needs 5 volt voltage. It supports the processors like 486 SX/SX2, DX/DX2, and DX4 OD (OverDrive). Its successor socket is Socket 2, Socket 3 and so on.

LGA1200 socket is the latest socket created by Intel to install10th generation and 11th generation Intel® Desktop Processors. However, 9th, 8th, 7th, 6th Generation Intel® Desktop Processors use LGA1151 socket.

Memory Slots and External Cache

The main memory of a computer is random access memory (RAM), which temporarily stores data during the normal operation of the computer. A memory slot is a physical connector on a motherboard of the computer that holds the main memory chip. It is very easy to identify on the computer motherboard.

Memory slots are long and located very close to each other on the motherboard. The number of slots of memory on the motherboard specifies the maximum amount of RAM that we can install on a computer. However, it may vary from motherboard to motherboard, but the appearance of different slots is the same.

Today, most of the computer’s motherboard come with DIMM (Dual In-line Memory Module) slots. They contain a series of dynamic random access memory (DRAM) chips mounted on a printed circuit board. They are designed in order to use in personal computers, workstations, printers, and servers.

Today, DIMMs come in a variety of sizes and speeds. They generally come in two lengths – for PC, it is 133.35 mm (5.25 in) and SO-DIMM for laptop is about half the size at 67.60 mm (2.66 in).

Variance of DIMMs support DDR, DDR2, DDR3, DDR4 and DDR5 RAM. DIMMs come in different pin configuration that are as follows:


  • 100-pin, used for printer SDRAM
  • 168-pin, used for SDRAM, FPM, EDO
  • 184-pin, used for DDR SDRAM
  • 200-pin, used for DRAM in some Sun workstations and servers.
  • 240-pin, used for DDR2 SDRAM, and DDR3 SDRAM
  • 240-pin, used for FB-DIMM
  • 278-pin, used for HP high density SDRAM.
  • 288-pin, used for DDR4 SDRAM and DDR5 SDRAM

SO-DIMM or small outline DIMM

  • 144-pin, used for SDR SDRAM
  • 200-pin, used for DDR SDRAM and DDR2 SDRAM
  • 204-pin, used for DDR3 SDRAM
  • 260-pin, used for DDR4 SDRAM
  • 260-pin, with different notch position, used for either DDR3 or DDR4 SDRAM
  • 262-pin, used for DDR5 SDRAM


  • 244-pin, used for DDR2 SDRAM


  • 172-pin, used for DDR SDRAM
  • 214-pin, used for DDR2 SDRAM

Note: The full form of DDR is double data rate. The full form of SDRAM is synchronous dynamic random-access memory (synchronous dynamic RAM).

Expansion Slots

Expansion slots are the most visible components of any motherboard. We can easily identify them on the motherboard, as they are generally located close to each other and near the rare end of the case. Expansion slots are usually 3 to 11 inches long and approximately 1/2 inch wide.

These slots are especially used to install various devices to expand its capabilities. We can install sound card, graphics cards, network card, etc on these slots. Each type of expansion slot differs in appearance and functions. The most common types of expansion slots on a typical motherboard of today’s computer are as:

  • PCI
  • AGP
  • PCIe

PCI Expansion Slots

Peripheral Component Interconnect (PCI) slots are found on the motherboard of a computer. They are used to connecting various compatible expansion cards or peripheral devices to the computer system.

These expansion slots allow us to add functionality and improve the performance of your computer. Most computers made today contain PCI slots. They can be easily identified because they are usually white and are about 3 inches long.

PCI slots can accommodate various types of expansion cards and peripherals. Here are some common devices that we can connect to PCI slots:

  • Graphics cards
  • Sound cards
  • Network Interface Cards (NIC)
  • Storage controllers
  • TV tuner cards
  • Wireless cards
  • Modems
  • USB expansion cards

AGP Expansion Slots

AGP stands for Accelerated Graphics Port or Advanced Graphics Port. It is a high-speed point-to-point channel for adding a 3D graphics card or video card to a computer’s motherboard. It allows the video card to communicate directly with the CPU processor and memory.

AGP slots can be easily recognizable because they are usually brown, located right next to the PCI slots on the motherboard. They are usually shorter than PCI slots.

PCIe Exapansion Slots

Peripheral Component Interconnect Express (PCIe) is a high-speed serial bus interface that we use to add various expansion cards to a motherboard of the computer system. It is available on new computer motherboards. This slot is designed to replace AGP and PCI slots, but most computer motherboards have still PCI aw well as AGP slots.

A PCIe slot establishes a direct and faster connection between the motherboard and peripherals, resulting in improved data transfer rates and reduced latency compared to their predecessors. We can use these slots to install graphics cards, network adapters, storage expansion, sound cards, video capture cards, etc.


The Basic Input/Output System (BIOS) or firmware is the most important semiconductor chip on the motherboard, aside from the processor. It is a non-volatile memory chip containing BIOS software that stores firmware instructions and data essential for the initial startup of a computer.

It basically tells the CPU processor how to interact with the rest of the hardware components of the computer. BIOS memory chip is activated as soon as the computer is powered on. When we turn on our computer, the BIOS chip executes a series of firmware instructions stored in its memory.

These instructions perform several essential tasks, such as testing hardware components, initializing system settings, and loading the operating system into memory. This process is called booting up.


Complementary metal-oxide semiconductor (CMOS) is a type of memory chip that stores certain computer settings, such as date and time, even when the computer is powered off. It gets its power from the small cylindrical battery, called CMOS battery, installed on the computer motherboard.

This battery comes in different shape and size, but they all perform similar functions. CMOS technology is widely used in analog circuits, such as image sensors, data conversion, and highly integrated transceivers for the various types of communication.

Cooling Systems

We know that electronic components produce heat. It is caused by the flow of electric current within the components.The components of a computer works better when kept cool. If heat is not removed, then it may run slower. The computer components may damage if too much heat generated.

When air will flow inside the computer case, it will remove heat. More air will flow, more will heat remove. To overcome this problem, a case fan is installed in the computer case to make the cooling process more efficient.

Besides to this case fan, a heat sink exhausts the heat away from the core of the processor. A case fan on the top of the heat sink does to remove the heat from the CPU.

Power Supply Connectors

Power connectors play a significant role in distributing the necessary electrical power to various components within a computer system. There is only one main power supply connector on the computer motherboard. It also contains a small 4-pin connector for CPU fan.

It can be easily recognisable because it is rectangular in shape and white in color. ATX (Advanced Technology eXtended ) power connector is widely used on the desktop computer and provides the electric power to the motherboard.

The main function of power supply is to convert 110-volt or 220-volt AC voltage into DC voltage for different components of the computer. These DC voltages supply 3.3 volts, +5 volts, and -5 volts, +12 volts and -12 volts. The rating of power supply unit is watts, that is a measure of power.

There are many different types of power supply connectors used on the motherboard and peripherals. Some of the common types of types are as:

  • 24-pin ATX power connector
  • 4/8-pin CPU power connector
  • PCIe power connector
  • SATA power connector
  • Molex power connector
  • Fan power connector

In this tutorial, we have discussed the components of computer motherboard and their functions in easy words. Hope that you will have understood the basic points of motherboard components with figure and enjoyed this tutorial.
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