Parts Of A Computer And Their Functions (All Components)

Whether you need to know the essential parts of a computer and their functions for academic reasons or to begin immersing yourself in the world of computers, this is the right resource for you.

Some parts include the case, motherboard, CPU, RAM, graphics card, SSD, HDD, keyboard, and mouse. Read on to discover more about the functions of all components.

Parts Of A Computer And Their Functions

Computer components and all their functions diagram.

1. The computer case or chassis

A standard empty computer case.

This component holds all of the physical parts of a computer system.

It is usually designed in such a manner to make fitting a motherboard, wiring, and primary and secondary storage devices as easy as possible. Some are designed so well that it is easy to make everything look tidy and presentable.

They can also accommodate CD or DVD drives, allowing users to listen to music using compact discs or watch Blu-ray movies from their computer.

Cases come in all different sizes and shapes to accommodate various computer components and satisfy the consumer’s needs. Not only do computer builders need to ensure compatibility between components, but also the case.

Cases typically have extra connectors on the front of them for more convenience. USB ports and headphone jacks are commonly found.

Design elements can vary from plain to highly elaborate. You can get a plain grey desktop case or one with colored lighting everywhere to make it look spectacular.

Computer cases rely on fans inside them to create proper airflow to keep all the internals cool and working reliably.

A computer case, like most things, varies in quality. You can get them made from cheap metals or good quality materials that provide you with a sturdy design.

A good way to discharge yourself from electrostatic charge before working on a computer is to touch the case. It will safeguard the computer’s circuits from being damaged by static discharge.

And, of course, a ground strap is recommended where possible.

Laptops have their case or chassis designed specifically for each model to hole all the parts and the screen in a conveniently compact design that can fold closed to make it even more mobile.

List of computer case sizes (known as form factor):

  • Very small form factor: Supports Mini ITX motherboards
  • Small form factor: Supports micro ATX motherboards.
  • Standard form factor: Supports standard ATX motherboards.
  • Larger form factors: Supports ATX and XL-ATX motherboards.

2. Motherboard

A standard desktop motherboard.

The motherboard is the main board mounted directly inside the computer case. All other cards plug directly into the motherboard, hence its name.

It is a printed circuit board in which the CPU, RAM, drives, power supply, expansion cards, and more are plugged into it.

Its function involves integrating all the physical components to communicate and operate together.

A good motherboard offers a wide amount of connectivity options. It also has the least amount of bottlenecks possible.

This allows all the components to operate efficiently and to fulfill their maximum potential as they were designed to do.

As the physical size is reduced, it limits connectivity options and functionality.

Motherboards come in the following sizes:

Pico-ITX3.9 inch x 2.9 inch | 100mm x 72mm
Nano-ITX4.7 inch x 4.7 inch | 120mm x 120mm
Mini-ITX6.7 inch x 6.7 inch | 170mm x 170mm
Micro-ATX9.6 inch x 9.6 inch | 244mm x 244mm
Standard-ATX12 inch x 9.6 inch | 305mm x 244mm
XL-ATXEVGA: 13.5 inch x 10.3 inch | 343mm x 262mm
Gigabyte: 13.58 inch x 10.31 inch | 345mm x 262mm
Micro-Star: 13.6 inch x 10.4 inch | 345mm x 264mm

3. Central Processing Unit (CPU)

A computer's CPU.

The CPU or central processing unit is basically like the brain of computer systems. It processes all the information on a computational level.

It takes all the processes from the RAM and processes them to perform the tasks required by the computer system.

The faster the processor, the more instructions it can execute at any given time.

The central processing unit is usually seated in a socket that utilizes a lever or a latch with a hinged plate with a cut-out in the center to secure the CPU onto the motherboard.

It has many copper pads underneath it for the socket contacts to push up against them to make electrical contact.

There are other ways CPUs can be attached to the motherboard.

Here are some common examples:

  • ZIF (Zero Insertion Force): Although this is a more desirable socket, they are mostly found on older computer motherboards. It has a lever-operated mechanism to clamp the pins of the processor.
  • PGA (Pin Grid Array): It is also a ZIF socket with a different pin pitch and count.
  • LGA (Land Grid Array): More commonly found on motherboards today. A levered hinged plate with a center cut-out clamps down on the processor.
  • BGA (Ball Grid Array): The CPU is soldered directly onto the motherboard. This makes it a non-user-swappable component. It is susceptible to bad connectivity.

A processor generates a decent amount of heat, especially when working under high loads.

It will run even hotter when set to a higher clock speed to make it run faster. This is called overclocking.

This is why a heatsink and fan assembly are required to draw the heat away from the central processing unit and distribute it to thin sheets or fins of metal for the fan to cool down.

There are so many different types of computer processors. The largest manufacturers of processors are Intel, AMD, and NVidia.

4. Random Access Memory (RAM)

A desktop computer's RAM modules or sticks.

RAM is a data storage device that can provide fast read and write access. RAM is volatile memory, meaning it loses all the stored data when power is lost.

The RAM keeps data ready for the CPU to process. The RAM speed is a big contributor to the overall speed of a computer system.

It plugs directly into a long slot that has contacts on either side of the slot.

It, too, has a clock speed, just like a processor. So, it can also be overclocked to deliver increased performance beyond the intended specification.

Certain RAM modules are sold with a heat spreader. It helps dissipate the heat from the individual memory ICs, keeping them cooler.

RAM has evolved like any other component. RAM used on the motherboard often uses DDR (Double Data Rate) SDRAM (Synchronous Dynamic Random Access Memory) type memory.

RAM Amount always comes in powers of 2, so you will always see numbers like 16GB, 32GB, or 64GB of RAM, to mention some examples of memory units.

5. Graphics Card or Graphics Processing Unit (GPU)

A computer's graphics card with three cooling fans.

A graphics card is an output device that processes the data from the motherboard and sends the appropriate information to the computer’s screen for display.

You can connect monitors to it using HDMI, DisplayPort, DVI, or VGA connectors.

It can also be referred to as a video or display card.

A video card takes the burden of all the video processing from the main CPU. This gives a computer a big boost in performance.

Fans are almost a given because of the large processing requirements for a gaming GPU.

A video card plugs into a PCI Express (Peripheral Component Interconnect Express) slot on the motherboard. It is a serial expansion bus slot capable of high bandwidth in two directions.

A graphics card has a GPU (Graphics Processing Unit), the main part of a computer system that requires cooling.

A GPU is slower than a CPU but is designed to deal with mathematical operations required for video rendering.

The card’s memory amount varies depending on the manufacturer’s design.

Video cards use GDDR (Graphics Double Data Rate) SDRAM, specially designed to optimize graphics performance.

GDDR is built to handle a higher bandwidth compared to plain DDR RAM.

A laptop’s GPU is usually mounted directly onto the motherboard, much like the CPU. Some models use integrated graphics with the GPU and CPU in one processing unit.

This can also be true for some CPUs for a desktop computer. The GPU can be integrated with the CPU, and the motherboard’s output ports are used instead of a graphics card’s ports.

Integrated graphics do not offer great performance, so most gamers or individuals using their computers for work that involves more GPU-intensive tasks opt for systems with discrete GPUs.

6. Sound Card

A PCIe sound card.

Most of the time, the sound chip built into the motherboard is used for audio output.

But, if you are a sound enthusiast or prefer high-quality audio output while playing a game, you might be inclined to use a sound card.

Sound cards plug into a computer in multiple ways. It can be through USB, PCI slot, or PCI Express x 1 slot.

External DACs have gained popularity and help deliver clearer and more defined audio or high-definition sound output.

They connect up using an IO cable like a USB cable to your computer or laptop and provide a line out for your speakers or headphones.

A sound processing chip on the card does all of the audio processing and is usually not a very powerful processor.

A sound card can offer a wide range of connectivity with audio equipment.

Examples could be optical audio, a 1/4-inch jack, or RCA connectors.

7. Hard Disk Drive (HDD)

A 3.5 inch hard drive next to a laptop 2.5 inch HDD.

A hard drive is still found in many PCs to this day. A mechanical drive’s purpose is to store all your information for retrieval at any time.


Apart from storing information for your computer, hard disk drives also function as a boot drive to run the operating system (OS) from it. You can install operating systems of many different kinds depending on your needs.

An OS is a software program installed, making a computer useable, like Microsoft Windows. The biggest vulnerability of a mechanical drive is its physically fragile nature.

They have fragile components

One bump the wrong way can destroy a whole drive. A mechanical hard drive contains one or more platters that spin anywhere between 5200 to 10000 RPM (revolutions per minute).

The read and write heads are about 0.002 (51 micro M) inches from the platter.

This gives you an idea about the physical limitations of its fragile nature.

Small areas on the platter can represent a 1 or a 0. It can be changed using the drive head to alter the material to represent the correct value magnetically. This is how to write data to the drive for storage.

There are various categories of hard drives made for various real-world applications.

Some examples include:

  • General use for desktops or laptops.
  • Gaming optimized for desktops or laptops.
  • General high-capacity storage.
  • NAS Devices.
  • Servers.
  • Video recording.

They can also be purchased as an external drive that usually connects to your computer by USB cable.

An uninterruptible power supply is sometimes used to prevent data loss with mechanical drives where a sudden power outage is experienced, or the power cord is accidentally disconnected while the computer is running.

This allows proper shutdowns for desktop systems that have experienced sudden power loss.

8. Solid State Drive (SSD)

An M.2 and SATA SSD is placed on one another.

An SSD is also a type of hard drive, but it doesn’t have any moving bits. It consists of a bank of flash memory that can hold a reasonable amount of information.

While the capacity of SSDs is increasing, they aren’t cost-effective for storing large amounts.

A mechanical drive has a cheaper gigabyte-to-dollar ratio.

However, the SSD is a high-performance drive. It’s fast and cannot be as easily damaged by dropping it or taking a few bumps.

SSDs are available as 2.5-inch laptop encapsulated drives, and an M.2 SDD is the most commonly used kind on the market.

That’s why I always recommend SSDs for portable-type computers where possible. In our other article, you can read more about whether or not SSD’s are worth it.

9. Power Supply Unit (PSU)

A standard desktop computer power supply.

A power supply unit mounts inside the computer case. It converts the AC mains supply from the power cord from a wall socket and supplies the correct DC voltages to all the parts of a computer.

A computer power supply supplies the following voltages:

  • +3.3v: This voltage is supplied to the motherboard.
  • +5V: This voltage is supplied to the motherboard and other computer hardware.
  • +12V: This voltage is supplied to the motherboard and other components.
  • -12V: This voltage is supplied to the motherboard.

One of the most important system components

It plays an important role in keeping a computer running reliably.

You get different wattage ratings for power supplies. The higher the wattage, the higher the electrical current that can be made available to everything that needs it to function properly.

The higher you go in Watts, the more the power supply will likely cost.

A power supply usually also comes with a cooling fan. This helps all the internal components in your computer to stay cool when the power supply is subjected to bigger loads.

You read more about a power supply and its lifespan to know how long it lasts.

10. Monitor or Visual Display Unit (VDU)

A standard computer monitor.

A monitor is an output device to visualize the graphics information sent from the computer’s GPU.

There are various types of monitors on the market. An LED (Light Emitting Diode) backlit LCD (Liquid Crystal Display) monitor is the most commonly used with a modern PC.

There are also various computer screen sizes with different aspect ratios. The aspect ratio is simply the ratio between height and width.

For example, a 16:9 aspect ratio screen will have 16 parts wide to 9 parts in height.

There are also curved computer monitors, but they are more expensive displays.

Monitors also have a fast response time to meet the high demands required to eliminate delays with user input for gaming.

11. Keyboard

A standard computer keyboard with 101 keys.

A keyboard is an input device that is one of the ways to communicate with a computer. Typing a key from the keyboard sends a small portion of information to tell it which key was pressed.

Once the computer receives input from the keyboard, it can use the keystrokes in digital form to produce a specific task in any software being used.

The computer system can use this information in many ways. An example could be a command or a character that can be used in a document.

There are two main different types of keyboards. Mechanical and membrane types.

12. Mouse or Trackpad

A standard wired computer mouse.

A mouse is an input device that allows the user to move a pointer displayed on the monitor and experience a more intuitive interaction with computer systems.

These days, mice have more buttons than the common three and offer way more functions than mice in the early days.

However, the three main buttons allow users to select, grab, scroll, and access extra menus and options.

A computer mouse is a handy pointing device that can be wired or wireless. The latter requires batteries.

Optical mice of today allow for very accurate precision and smooth movement.

Laptops have a built-in trackpad, which works almost like a mouse. Many people don’t like working with them, so they usually plug a mouse into the laptop instead.

Common peripheral parts for computers

Some common peripherals connect to a computer and extend their usefulness.


A computer printer.

A printer can take an image sent by a computer and deliver it onto a sheet of paper.

It does this by using the information from the computer, and by either using toner or ink, it deposits one of these in a controlled and accurate manner to form the image.


A flatbed computer scanner.

A scanner can take anything on paper, and it functions by scanning it to produce a replicated digital image for a computer to save.

This is also handy for saving physical photos you want to preserve.

Once the photo is stored digitally, it won’t decay as a physical photo does over time.

The flatbed scanner is one of the most commonly used today.

Multifunction printers

A multifunction printer is being used.

Many all-in-one, multifunction devices have printer and scanning capabilities in one reasonably compact product, which has dominated the market over recent years and continues to grow.

The most common models include an inkjet printer and scanner for home use and a laser printer version for home and other office applications.

Computer Speakers

A pair of desktop computer speakers.

Speakers can connect to the sound card at the rear of the computer.

Another way they can be connected is by a monitor that already has built-in speakers.

For more full immersion

Generally, the sound quality is poor from a monitor’s speakers. That’s why most people buy a set of computer speakers for their desks.

You can even connect up a 7.1 surround speaker system to certain sound cards for a computer.

This can add a nicer experience to gaming, playing music, or watching a film.

A microphone

A microphone is set up with a computer.

A microphone is essential for anyone who requires decent audio recording or capturing. They can range widely in price, from extremely cheap to very expensive, depending on the individual’s profession or application.

They are usually connected to an audio interface before connecting to the computer.

There are so many uses for a microphone connected to a computer, but some include:

  • Recording singing or musical instruments for composing music.
  • Game streaming or commentary.
  • Communication for calls.
  • Webinars.
  • Creating podcasts.

A camera or webcam

A computer webcam or camera attached to a monitor.

Desktop users often use cameras when not using a laptop or other portable communication device with an inbuilt camera.

Again, quality can vary depending on how much someone is willing to spend. They allow many applications, including video or conference calls, webinars, or presentations, and gamers to be streamed from their seats.

Many models have microphones built into them, but they won’t deliver the audio quality that a high-end dedicated microphone can produce.

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