Parts of a Motherboard and Their Function

Updated on March 22, 2017
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Patrick is a dedicated writer who wishes to make the world better by informing individuals who seek more knowledge.

The Parts of a Computer Motherboard

Some of the major components of a motherboard.
Some of the major components of a motherboard.

The main printed circuit board in a computer is known as the motherboard. Other names for this central computer unit are system board, main board, or printed wired board (PWB). The motherboard is sometimes shortened to Mobo.

Numerous major components, crucial for the functioning of the computer, are attached to the motherboard. These include the processor, memory, and expansion slots. The motherboard connects directly or indirectly to every part of the PC.

The type of motherboard installed in a PC has a great effect on a computer's system speed and expansion capabilities.

Major Motherboard Components and Their Functions

A labeled ASRock K7VT4A Pro Mainboard.
A labeled ASRock K7VT4A Pro Mainboard. | Source

Central Processing Unit (CPU)

Also known as the microprocessor or the processor, the CPU is the computer's brain. It is responsible for fetching, decoding, and executing program instructions as well as performing mathematical and logical calculations.

The processor chip is identified by the processor type and the manufacturer. This information is usually inscribed on the chip itself. For example, Intel 386, Advanced Micro Devices (AMD) 386, Cyrix 486, Pentium MMX, Intel Core 2Duo, or iCore7.

If the processor chip is not on the motherboard, you can identify the processor socket as socket 1 to Socket 8, LGA 775 among others. This can help you identify the processor that fits in the socket. For example, a 486DX processor fits into Socket 3.

Random Access Memory (RAM)

Random Access Memory, or RAM, usually refers to computer chips that temporarily store dynamic data to enhance computer performance while you are working.

In other words, it is the working place of your computer, where active programs and data are loaded so that any time time the processor requires them, it doesn't have to fetch them from the hard disk.

Random access memory is volatile, meaning it loses its contents once power is turned off. This is different from non-volatile memory, such as hard disks and flash memory, which do not require a power source to retain data.

When a computer shuts down properly, all data located in RAM is returned back to permanent storage on the hard drive or flash drive. At the next boot-up, RAM begins to fill with programs automatically loaded at startup, a process called booting. Later on, the user opens other files and programs that are still loaded in the memory.

Basic Input/Output System (BIOS)

BIOS stands for Basic Input/Output System. BIOS is a "read only" memory, which consists of low-level software that controls the system hardware and acts as an interface between the operating system and the hardware. Most people know the term BIOS by another name—device drivers, or just drivers. BIOS is essentially the link between the computer hardware and software in a system.

All motherboards include a small block of Read Only Memory (ROM) which is separate from the main system memory used for loading and running software. On PCs, the BIOS contains all the code required to control the keyboard, display screen, disk drives, serial communications, and a number of miscellaneous functions.

The system BIOS is a ROM chip on the motherboard used during the startup routine (boot process) to check out the system and prepare to run the hardware. The BIOS is stored on a ROM chip because ROM retains information even when no power is being supplied to the computer.

Complimentary Metal Oxide Semiconductor Random Access Memory (CMOS RAM)

A CMOS battery.
A CMOS battery.

Motherboards also include a small separate block of memory made from CMOS RAM chips which is kept alive by a battery (known as a CMOS battery) even when the PC’s power is off. This prevents reconfiguration when the PC is powered on.

CMOS devices require very little power to operate.

The CMOS RAM is used to store basic Information about the PC’s configuration for instance:-

  • Floppy disk and hard disk drive types
  • Information about CPU
  • RAM size
  • Date and time
  • Serial and parallel port information
  • Plug and Play information
  • Power Saving settings

Other Important data kept in CMOS memory is the time and date, which is updated by a Real Time Clock (RTC).

Cache Memory

L2 cache on an old motherboard.
L2 cache on an old motherboard.

Cache memory is a small block of high-speed memory (RAM) that enhances PC performance by pre-loading information from the (relatively slow) main memory and passing it to the processor on demand.

Most CPUs have an internal cache memory (built into the processor) which is referred to as Level 1 or primary cache memory. This can be supplemented by external cache memory fitted on the motherboard. This is the Level 2 or secondary cache.

In modern computers, Levels 1 and 2 cache memory are built into the processor die. If a third cache is implemented outside the die, it is referred to as the Level 3 (L3) cache.

Expansion Bus

PCI slots.
PCI slots.

An expansion bus is an input/output pathway from the CPU to peripheral devices and it is typically made up of a series of slots on the motherboard. Expansion boards (cards) plug into the bus. PCI is the most common expansion bus in a PC and other hardware platforms. Buses carry signals such as data, memory addresses, power, and control signals from component to component. Other types of buses include ISA and EISA.

Expansion buses enhance the PCs capabilities by allowing users to add missing features in their computers by slotting adapter cards into expansion slots.


A chipset is a group of small circuits that coordinate the flow of data to and from a PC's key components. These key components include the CPU itself, the main memory, the secondary cache, and any devices situated on the buses. A chipset also controls data flow to and from hard disks and other devices connected to the IDE channels.

A computer has got two main chipsets:

  • The NorthBridge (also called the memory controller) is in charge of controlling transfers between the processor and the RAM, which is why it is located physically near the processor. It is sometimes called the GMCH, for Graphic and Memory Controller Hub.
  • The SouthBridge (also called the input/output controller or expansion controller) handles communications between slower peripheral devices. It is also called the ICH (I/O Controller Hub). The term "bridge" is generally used to designate a component which connects two buses.

Chipset manufacturers include SIS, VIA, ALI, and OPTI.

CPU Clock

The CPU clock synchronizes the operation of all parts of the PC and provides the basic timing signal for the CPU. Using a quartz crystal, the CPU clock breathes life into the microprocessor by feeding it a constant flow of pulses.

For example, a 200 MHz CPU receives 200 million pulses per second from the clock. A 2 GHz CPU gets two billion pulses per second. Similarly, in any communications device a clock may be used to synchronize the data pulses between sender and receiver.

A "real-time clock," also called the "system clock," keeps track of the time of day and makes this data available to the software. A "time-sharing clock" interrupts the CPU at regular intervals and allows the operating system to divide its time between active users and/or applications.

Switches and Jumpers

  • DIP (Dual In-line Package) switches are small electronic switches found on the circuit board that can be turned on or off just like a normal switch. They are very small and so are usually flipped with a pointed object, such as the tip of a screwdriver, a bent paper clip, or a pen top. Take care when cleaning near DIP switches, as some solvents may destroy them. Dip switches are obsolete and you will not find them in modern systems.
  • Jumper pins are small protruding pins on the motherboard. A jumper cap or bridge is used to connect or short a pair of jumper pins. When the bridge is connected to any two pins, via a shorting link, it completes the circuit and a certain configuration has been achieved.
  • Jumper caps are metal bridges that close an electrical circuit. Typically, a jumper consists of a plastic plug that fits over a pair of protruding pins. Jumpers are sometimes used to configure expansion boards. By placing a jumper plug over a different set of pins, you can change a board's parameters.

NOTE: You can check the jumper pins and jumper cap at the back of an IDE hard disk and a CD/DVD ROM/Writer.

Parts of a Motherboard

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© 2011 Patrick Kamau


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    • profile image

      Deepak singh 6 days ago

      Very good

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      komalpreet 10 days ago

      very easy function. good

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      Nana Kofi Arhin 4 weeks ago

      Wow, there was nothing left out to explain, good work done, simple and very clear

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      Eunice 5 weeks ago

      Well explained. Thanks

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      priya 6 weeks ago

      wow superb explaination of motherboard by showing practical way ... thanks patrick for tthis video .

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      Lisah Charuma 6 weeks ago

      Very beneficial.... Simple, short and precise, just what i was looking for.... Thanx

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      Manjula SN 7 weeks ago

      Hey dude, Thank you for giving very good informations.

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      cristan what is the meaning of AGP? 7 weeks ago

      wahats is the meaning of PCI and SATA?

    • profile image

      Hardip Jogi 8 weeks ago

      Great info everything is explained very nicely easy to understand it helped so much cleared all my doubts. Thanks

    • profile image

      gagiya 2 months ago

      practically better and nice

    • profile image

      NOORYLAIN 2 months ago


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      chidimma miracle 2 months ago

      i needed the combined functions of the mother board.

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      lallu kumar yadav 2 months ago

      very nice

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      Tadiwa Moyo 2 months ago

      Thanks your notes are really beneficial

    • profile image 2 months ago

      I really like it! Its very detailed. It really helps me a lot for my tomorrows exam for NCII.Thank you for this @Patrick. Wish me luck!

    • profile image

      Anisha 2 months ago


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      Snehal 2 months ago

      Very nice

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      Very useful nice

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      Al 3 months ago

      fantastic site

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      Pandit Abhishek Pandey 3 months ago

      Fantastic video

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      iftikhar 3 months ago

      can we connect CCTV camera directly in mainbord of computer. or analog video source . and in which points we do that in computer hardware ?? is this possible??

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      Martin Seth 3 months ago

      Thank you Patrick even though am still going to go through the process but the information was of great help .God bless.

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      Aiku Samoka 3 months ago

      I found this Useful !

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      insider 3 months ago

      No, no, no. I needed the PCI in this!

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      David Ngobi 3 months ago

      The article is so informative, precise and concise, thank you so much!

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      gaurav 4 months ago

      It is so informative & I got job for reading this thank you so much

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      kritika 4 months ago


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      Gabriel 4 months ago

      Thanks i have got what i was looking ...i got knowledge about the c system

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      Tasawar Iqbal 4 months ago

      Very informative and interesting. . . . . .

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      machaah 4 months ago

      i am happy to see what i was looking for in this website

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      nano 4 months ago

      superb video

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      sheela 4 months ago

      it was soo helpful

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      leela 4 months ago

      nice video......

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      islok kumar 4 months ago

      this is great

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      Patrick Kamau 4 months ago from Nairobi, Kenya

      Hey sardar, what information were you looking for?

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      sardar 4 months ago

      no information about what i was looking

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      sssamuel 5 months ago

      Nice write up.

      Helped me in my assignments

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      yuvraj kalaskar 5 months ago

      im very happy for this blog it gives good informaton I'll score 10 pointer

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      gladys 5 months ago

      good for computer system servicing study helps me alot thanks..

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      samtie 6 months ago

      thanx so much

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      ANESU 6 months ago

      This site is so helpful ,

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      Muhammad Zaheer 6 months ago

      Best topic coverage. Good and very informative...

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      Motisagar 6 months ago

      Really It's bro.. Thank you

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      The Under Taker 6 months ago

      Really Good Job Patrick...

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      julius 6 months ago

      thanks so much for simplifying to us the parts of motherboard and their functions keep it up

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      Quentin 7 months ago

      Very Good Info Good Job could you make a website for other parts of the PC.

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      Kalpana 7 months ago


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      Patrick Kamau 7 months ago from Nairobi, Kenya

      You are welcome BUNUNU and thanks for visiting.

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      KA'AFAR MUSA BUNUNU 7 months ago

      thanks for this assistant

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      Anndrew Nyongesa 7 months ago

      good information indeed!!

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      Patrick Kamau 8 months ago from Nairobi, Kenya

      You are welcome poorna

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      Patrick Kamau 8 months ago from Nairobi, Kenya

      Thanks Jean Karlo Rocher for the visit.

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      Jean Karlo Rocher 8 months ago

      I don't have any comments

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      Patrick Kamau 8 months ago from Nairobi, Kenya

      You are much welcome EDWARD MULATI WEKALAO. Thanks

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      EDWARD MULATI WEKALAO 8 months ago

      thank you for the response it added vast understanding to my informational need.i appreciate.

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      Patrick Kamau 9 months ago from Nairobi, Kenya

      Hi Arnelgwapo, After creating your chart, right click on it and change the way Excel treats empty cells. To do this: Right click the chart and choose Select Data, Click Hidden and Empty Cells. Select how you want to show empty cells.

      You can also check this article for more information

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      arnelgwapo 9 months ago

      How to Get Excel 2007 and 2010 to Ignore Empty Cells in a Chart or Graph

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      Patrick Kamau 9 months ago from Nairobi, Kenya

      Hi Magenta, it is easy to join hubpages, you can use my referal tracker

      or simply go to HubPages site and create account.

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      Magenta Kumar 9 months ago

      Thank you for nice information about CPU and Motherboard

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      alburnas mutua 9 months ago

      thanks for the information it was helpful

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      Stephen 9 months ago

      This is good

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      kirdip 9 months ago

      great informtion i am student of class "10" of technical and it sector,,,,it really helped me in my exams and solvings the problems of parts of mother board....

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      Young_imran 10 months ago

      Good and fyn.. We really appreciate this site, GOD bless U

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      SYEDGanih was here 10 months ago

      Really nice

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      sam 11 months ago

      Soo helpful

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      bittu Choudhary 11 months ago

      Very very helpful for us, I can't explain

      Thanks a lot

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      capstran ngeti 11 months ago

      It really interesting

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      karan modi 11 months ago

      really....nice ...

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      JONATHAN J-STAR 11 months ago


    • profile image

      eddy 12 months ago

      its very interesting and helpful

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      12 months ago

      Thanks for this good job

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      Moksha Jain 12 months ago

      It is very helpful and NYC to project

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      Zebby 12 months ago

      Thanks so much Kamau, great stuff! I am doing A+ just started with Components of motherboard, your work was very helpful

      keep up the good job

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      Maven udom 12 months ago

      thanks a lot for the inspiation

    • Patkay profile image

      Patrick Kamau 12 months ago from Nairobi, Kenya

      You are much welcome Linslot sumo David and thanks for the visit. All the best.

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      mamadou barry 14 months ago

      thank you for the informtion

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      Bahath 15 months ago

      I'm glad to see this lesson.

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      Welles Dark 15 months ago


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      xx 15 months ago

      its really a helpful notes

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      jinsigoshal 15 months ago

      it's good but need more information about other parts also

    • profile image

      bank 15 months ago

      am a computer science student on industrial training feeling my log book i was to rite a report on motherboard and bios and here i am so good to be here thanks bro God will make you bigeer

    • profile image

      Atom 15 months ago

      I am doing a repot on motherboards and this is very helpful

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      Unknown 16 months ago

      thank you for helping me =)

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      Happy 16 months ago

      Thanks Patt

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      Enayat 16 months ago

      thanks for this article

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      Hans 16 months ago

      Great. Thank you very much Patrick.

      BR from Berlin.

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      kunjan 16 months ago

      thank you patric..................

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      muhammed fairooz 16 months ago

      it is very helpful

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      gurinder singh saini 16 months ago

      Good this is very helpful for me

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      sajan varpe 17 months ago

      thank you

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      ZEUS 17 months ago

      nice patkay ^+^ thank you

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      mitz 17 months ago

      nice one ya

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      manisha 17 months ago

      it's good-but need more information about other parts also

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      Emmanuel 18 months ago

      Thanks, may God give you More Grace, found this piece useful

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      Num Chucks 18 months ago

      its nice bro .. good job

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      Hitlar 18 months ago

      Thank you for this

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      mercy ruto 19 months ago

      Thanks a lot for sharing that much with us its beneficial to me.keep on sharing knowledge with IT guys.

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      @Christian 20 months ago

      This video is amazing now I can show this to my teacher she will give me A+ thanks Patrick :).

    • profile image

      rex ryan balaquinto 20 months ago

      its so nice that i learn about the parts and function of motherboard


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