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10 Parts of a Motherboard and Their Function

Patrick, a computer technician, 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 Computer Mother Board Explained

The main printed circuit board in a computer is known as the motherboard. Other names for this central computer unit are system board, mainboard, 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.

The Computer's Microprocessor

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.

The Computer Memory

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 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 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 memory.

The 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.

Photo Showing the CMOS Battery

A CMOS Battery.

A CMOS Battery.

The CMOS Battery

Motherboards also include a small separate block of memory made from CMOS RAM chips which are 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).

The Level 2 Cache Memory on an Old Motherboard

L2 cache on an old motherboard.

L2 cache on an old motherboard.

The Computer Cache Memory

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.

PCI slots.

PCI slots.

The Expansion Buses

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.

This introduction to computer bus article covers all of them including the new types.

The Computer Chip-sets

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.

The 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.

The 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.

More Resources

If you are on the lookout for more resources about computers, you can buy this book CompTIA A+ Certification All-in-One Exam Guide. This is a good book for those who want to know much more about computer hardware. I have used the book on numerous occasions and Mike Meyers never disappoints.

Parts of a Motherboard

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Questions & Answers

Question: What is the function of the PCI slot?

Answer: PCI stands for Peripheral Component Interconnect. This is a computer slot that allows you to insert expansion cards into your computer. These can come in the form of sound cards, RAID cards, SSDs, graphics cards, Coprocessors, and several other functional computer parts. So it enables you to expand the capabilities of the PC by adding what you do not have.

Question: How do I identify whether the RAM slots are DDR 1, DDR 2, DDR 3, or DDR 4?

Answer: There are a number of ways you can use to determine the kind of RAM slot you have. To begin with, you can check the number of pins. DDR has 184 pins and DDR2 and 3 has 240 pins while DDR4 has 288 pins. The other method is to look at the key notch position. DDR notch is almost at the center but slightly to the right. DDR2 notch is almost at the center as compared to DDR3 which is slightly to the left. DDR4 has a notch slightly to the right but very close to the center of the RAM slot.

Question: Why is thé network card not mentioned?

Answer: If you look at the article closely, we are talking about various components found on the motherboard. When it comes to the network card, you will find that most modern computers support an internal network interface controller embedded in the motherboard directly rather than provided as an external component. So, in modern motherboards, you will not find a network card as a device on its own. It will be embedded in a chipset.

Question: What is the function of IDE under system hardware?

Answer: Integrated Drive Electronics (IDE) is a standard interface for connecting a motherboard to storage devices such as hard drives and CD-ROM/DVD drives. In most older motherboards, there used to be 2 IDE channels where drives were connected via a ribbon cable. Each cable carries 2 devices. There is an integrated disk drive controller on the motherboard for controlling the flow of informing from the drive to the motherboard and vice versa.

Modern motherboards make use of SATA technology. A serial advanced technology attachment (serial ATA, SATA or S-ATA) is a computer bus interface used to connect host bus adapters (disk drive controllers) with mass storage devices like optical drives and hard drives.

Question: What are the functions of the south bridge Chipset?

Answer: The Southbridge chipset is the chip that controls all of the computers I/O (input-output) functions, such as USB, audio, serial, the system BIOS, the ISA bus, the interrupt controller and the IDE channels.

Question: What is C.M.O.S?

Answer: Looking at the dictionary you will get this definition;

a) "a technology for making low power integrated circuits.

b) a chip built using CMOS technology."

That is very true, inside the computer, there are what we call RAM chips normally referred to as the CMOS RAM. CMOS is an acronym for Complementary Metal Oxide Semiconductor. It is a technology used to fabricate or make integrated circuits used in most electronic and electrical fields. These ram chips loose power and hence has to be powered using a battery referred to as the CMOS battery. CMOS devices require very little power to operate. The CMOS RAM is used to store basic Information about the PC’s configuration.

Question: What is BIOS?

Answer: "BIOS" stands for "Basic Input Output System." It is software stored on a small memory chip on the motherboard. This software instructs the computer on how to perform some basic functions such as booting and keyboard control. BIOS is also used to identify and configure the hardware in a computer such as the hard drive, floppy disk drive, optical drive, CPU, memory, etc.

Question: What is RAM?

Answer: RAM or Random Access Memory is a high-speed type of computer memory which temporarily stores all the information your PC needs at the moment. It’s where your computer loads up all the things it thinks it will need to find out soon, so you can think of it as a working place of your computer. When it does need something, it fetches it super fast from the memory which is accessed randomly. Note that RAM is temporary storage; thus when the power goes off or when you switch off your computer, all data held in RAM is lost.

Question: What are beep codes from a motherboard?

Answer: Beep codes are audio signals given out by a computer to announce the result of a short diagnostic testing sequence the computer performs when first powering up (called the Power-On-Self-Test or POST). When you power on your computer, it has to test major devices such as RAM, Processor, Keyboard, and Drives among others. If any of the devices are faulty, you will receive a beep sound indicating which device has a problem.

Question: Which is the most important component of a computer system?

Answer: Technically speaking, I would say that each and every component is important. There are those who will be quick to reply that it is the processor. Yes, it is true the processor plays an important role in the computer. But what about the memory, can a computer operate without the memory? That is a big no. What about the power supply? Again can the computer operate without the power supply? That is not possible. So in simple words, all the components of a computer are very important as they are there are there for a reason.

© 2011 Patrick Kamau

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You are much welcome Niku Moni Boro. Keep reading even other works to gain more knowledge.

Patrick Kamau (author) from Nairobi, Kenya on September 15, 2018:

Thanks a lot Piper mcnutt for reading and commenting. I will surely try to add more information regarding the parts of the motherboard and their functions

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Patrick Kamau (author) from Nairobi, Kenya on August 23, 2018:

In a PC, graphics rendering originally took place in the CPU. Over time, functions were offloaded to separate circuits and then to GPUs either in separate cards, the PC's chipset or the CPU chip itself depending on the type of computer.

Muzammal on August 18, 2018:

Where is GPU???

MANOJ DUTTA on August 17, 2018:

Nice information. But I found it too long.....

Patrick Kamau (author) from Nairobi, Kenya on August 11, 2018:

Hello Peter, you can start by using the various parts of the motherboard that I have listed on this article.

Patrick Kamau (author) from Nairobi, Kenya on August 11, 2018:

Thanks, Sebusiso for appreciating the work in this article. I am glad you got what you wanted to know about different parts of the motherboard.

Peter on August 09, 2018:

Thank you sir, blessing follow you.

I need 15 internal device, location and their function