By the end of this lesson you will be able to
- Tell internal parts of a computer from external ones.
- Explain the job of the CPU, RAM, motherboard and graphics processor using a workbench comparison.
- Explain why RAM and storage are different things.
- Point to the main parts on a labelled motherboard picture.
- Match a common symptom, such as slowness or a distorted picture, to the part most likely to be involved.
When a computer feels slow, a salesperson says it has “8 gigabytes of RAM and a fast processor”, and you nod without knowing what that means. This lesson fixes that. You will learn the four main parts inside the box, what each one is for, and how they work together. That knowledge helps you buy sensibly, understand what is being offered, and describe a problem clearly when you ask for help.
Inside and outside
Parts of a computer fall into two groups. External parts are the ones you can see and plug in: the screen, keyboard, mouse, printer and speakers. Internal parts are hidden inside the case or under the keyboard on a laptop. They do most of the real work, and this lesson is about them.
- Screen or monitor
- Keyboard, mouse, touchpad
- Speakers, printer, webcam
- Charger and cables
Mostly input and output.
- Motherboard
- Processor (CPU)
- Memory (RAM)
- Storage drive
- Fan and graphics
Do the processing and keeping.
Read this figure as text
Two columns listing external parts such as screen and keyboard, and internal parts such as processor, memory and motherboard.
External parts, which you can see and usually unplug: screen or monitor, keyboard, mouse or touchpad, speakers, printer and the charger. Internal parts, hidden inside the case: the motherboard that everything plugs into, the processor (CPU), the memory (RAM), the storage drive, a cooling fan, and sometimes a separate graphics card. External parts are mostly for input and output; internal parts do the processing and keeping.
A workbench comparison
Picture a carpenter in a workshop. The carpenter is the processor: the one who does the actual work, one small step at a time. The workbench is memory: the surface where the tools and wood for today's job are laid out within easy reach. The cupboard at the back of the shop is Storage: it holds everything you own, but anything in it must be carried to the bench before it can be used.
- Does the work step by step
- Speed: how quickly it works
- Cores: how many work at once
Decides how fast work is done.
- Holds what you use right now
- Very fast to reach
- Emptied when power goes off
Decides how much you can have open.
- Keeps files and programs
- Holds far more than RAM
- Keeps contents when off
Decides how much you can keep.
Read this figure as text
Three columns comparing the processor to a carpenter, RAM to a workbench and storage to a cupboard.
Processor (CPU) is the carpenter: it does the work, one small step at a time. A faster or multi-core processor is like a quicker carpenter, or several carpenters. Memory (RAM) is the workbench: it holds what you are working on right now. A bigger bench holds more jobs at once, but it is cleared when the lights go out. Storage (SSD or hard disk) is the cupboard: it keeps everything for good, even when the power is off, but it is slower to fetch from than the bench.
The processor (CPU)
You met the processor's fetch, decode and do cycle in Module 1. Two numbers on a specification sheet describe it. The first is clock speed in gigahertz (GHz): how fast it ticks. The second is the number of cores: a core is one complete working unit, so a processor with four cores can follow four streams of instructions at the same time. Two cores are enough for light use such as writing and browsing; more cores help when you do many things together or heavy jobs such as editing video.
The processor gets hot when it works hard, so it sits under a Heatsink, a block of metal fins, usually with a fan on top. On a laptop this is hidden inside. If the cooling is blocked with dust, the processor slows itself down to protect itself, which makes the laptop sluggish.
Memory (RAM)
RAM stands for random access memory. It is the computer's short-term workspace. When you open a program or a document, a copy is placed in RAM because RAM is far faster to reach than storage. RAM is measured in gigabytes. More RAM means you can keep more programs and browser tabs open before the computer has to shuffle things around. When RAM fills up, the computer uses part of storage as an emergency overflow area, and everything slows down noticeably.
The motherboard
The Motherboard is the main circuit board. Every other part either plugs into it or is attached to it, and its printed copper tracks carry signals between them. If the parts are people, the motherboard is the building with all its corridors. Look for these parts on the picture: the socket where the processor sits, the slots for RAM, a slot for a separate graphics card, a small slot for an SSD, and the connector that brings in power.
Read this figure as text
A drawn motherboard with numbered markers on the processor socket, RAM slots, chipset, graphics slot, SSD slot and power connector.
A desktop motherboard seen from above. Marker 1 is the CPU socket where the processor sits under its cooler. Marker 2 is the RAM slots where memory sticks plug in. Marker 3 is the chipset, which coordinates traffic between the parts. Marker 4 is the graphics card slot (PCIe). Marker 5 is the M.2 slot that holds a small stick-shaped SSD. Marker 6 is the main power connector. Marker 7 is the coin-sized clock battery that keeps the clock running while the computer is off. Laptop motherboards are smaller and more tightly packed, but have the same kinds of parts.
Read this figure as text
A drawing of the inside of a desktop computer case with numbered parts: motherboard, processor with cooler, RAM, graphics card, storage, power supply and fan.
The inside of a desktop tower. The motherboard is the large board against the side wall. The processor with its cooler sits near the top of the board, with RAM sticks next to it. The graphics card plugs into the long slot lower down. A storage drive is fixed near the front. The power supply, a metal box at the bottom, feeds every part. A case fan moves air through the box. Never open the power supply: it can hold a dangerous electric charge.
Graphics
Everything you see on the screen has to be worked out as a grid of coloured dots, many times a second. The part that specialises in this is the graphics processor. It is very good at doing thousands of small, similar calculations at once. Most laptops have built-in graphics, which is part of the processor chip and is fine for documents, browsing and video. Computers for games, 3D design or heavy video editing often have a separate graphics card with its own memory. If you do not play games or edit video, you do not need one.
What it feels like when a part struggles
You cannot see inside a laptop, but the symptoms point to a likely part. Use the table as a guide to ask better questions, not as a diagnosis. Many of these symptoms have simple causes such as too many open programs or an update running in the background.
| What you notice | Part most likely involved | First things to try |
|---|---|---|
| Everything is slow when many tabs and programs are open | RAM is full | Close programs and tabs you do not need, then restart. |
| The computer slows down and the fan is loud and the base is hot | Cooling and the processor | Put it on a hard flat surface and check the vents are not blocked. |
| The picture flickers, shows stripes or odd colours | Graphics or the display cable | Restart. If it also appears on an external monitor, tell a technician. |
| The computer will not start at all and nothing lights up | Power or the motherboard | Check the charger and socket first; see the power lesson. |
| Beeps or flashing lights at start, no picture on a desktop | RAM or graphics not seated properly | Do not open the case; ask a technician. |
Practise connecting the CPU, RAM, storage, graphics and motherboard to what each one does.
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Common mistakes
✖ Instead of: Saying “my computer has 8 GB of memory” when meaning the storage drive.
✔ Do this: Say RAM for the short-term workspace and storage (or SSD) for the place where files are kept. Mixing them up leads to buying the wrong thing.
✖ Instead of: Assuming a higher GHz number always means a faster computer.
✔ Do this: Clock speed is one factor. Cores, processor design, RAM and whether the storage is an SSD all matter as well.
✖ Instead of: Opening the case or laptop to look at the parts out of curiosity.
✔ Do this: Look at the pictures instead. Inside a computer there are delicate parts, and a desktop power supply can hold a dangerous charge even when unplugged.
If something goes wrong
- I cannot find the About page in Settings.
- On Ubuntu 24.04, open Settings and choose System at the bottom of the left-hand list, then About. On Windows 11, open Settings, choose System, then scroll down to About. The labels can differ slightly between releases.
- The About page shows names I do not recognise, such as a long processor code.
- That is normal. Copy the code into a web search along with the word “processor” to see the maker's description, or just note the number of cores and the maker's name.
- I cannot tell whether my laptop has a separate graphics card.
- Most laptops for office and study use built-in graphics. If the specification does not mention a named graphics card, it almost certainly uses built-in graphics.
Key terms
- CPU
- The part of a computer that carries out instructions; its main thinking chip.
- RAM
- The computer's short-term working space, which holds what you are using right now and is emptied when it switches off.
- Motherboard
- The main circuit board that every other part of the computer plugs into.
- GPU
- A chip that specialises in drawing images and video on the screen.
- Core
- One complete working unit inside a processor. More cores let it do several jobs at the same time.
- Clock speed
- How many tiny steps per second a processor's internal clock ticks, measured in gigahertz (GHz).
Practise it for real
Reading is not the same as being able to do it. Complete these on your own computer, then tick only what you have actually done. These ticks are your own honest record: nothing checks them for you.
Read a computer's specification
On your own laptop, open Settings and look for the About page (on Ubuntu: Settings, then System, then About; on Windows 11: Settings, then System, then About). Find the processor name, the amount of installed memory (RAM) and the operating system. Write each one down and say which part of the workbench comparison it is: carpenter, bench or cupboard.
Challenge: compare two laptops on paper
Open any two laptop product pages from shops you trust, or use two printed leaflets. For each laptop write the processor, number of cores if shown, RAM, storage type and size. Decide which would suit a student who writes, browses and watches videos, and explain your choice in two sentences using the words processor, RAM and storage correctly. Do not buy anything; this is practice.
Knowledge check
7 questions. You need 80% to pass. Mistakes here are part of learning, and you can retry as often as you like.
Summary
- Internal parts do the processing and keeping; external parts are mostly for input and output.
- Workbench comparison: the processor is the carpenter, RAM is the bench, storage is the cupboard.
- More cores and more RAM help with many tasks at once; RAM empties when the power is off.
- The motherboard joins every part together; graphics produces the picture.
- Symptoms such as slowness, heat or a flickering picture point to likely parts but are not proof.
Checklist: can you do these?
Marking a lesson as read does not prove you can do it. Skills count as demonstrated when you pass the quiz (not yet) and complete the practical tasks (not yet).
Related lessons
References and further reading
Official sources for details that can change between versions.
- Computer basics: inside a computer (GCFGlobal)
- How computers work (BBC Bitesize, computing) (BBC Bitesize)