COMPUTER TECHNOLOGY
Section 2
Hardware on the Inside
Section 1 covered the parts you can see and plug in. This section opens the case: the power supply, the motherboard, the processor, the memory and the drives that do the actual work.
A look inside, power, the board
Slides 2–6
Processors and cooling
Slides 7–10
RAM, ROM and firmware
Slides 11–15
Ports, storage, recap
Slides 16–19
Components Inside a Computer
Take the side off a desktop and this is roughly what you find. The processor sits in the middle of the board underneath its cooler. The graphics card slots in below it, the memory stands in a row alongside, and fans move air through the case around all of it.
Every one of these parts gets a slide of its own from here on.
the parts of a desktop, labeled
Not everything is labeled
The power supply usually hides in a compartment at the bottom, and the storage is a small stick clipped flat to the board rather than a drive in a bay.
Airflow matters
Fans pull cool air in at the front and push warm air out at the back. Block either end and the machine runs hot and slows itself down.
Before you open one
Unplug it first, and touch the bare metal frame to discharge static. A shock too small to feel can still kill a chip.
Power it Up!
Every computer needs a power supply. It takes electricity and converts it into a current that works for the computer. It has to supply the exact or near exact voltage at the required wattage to all of the circuitry inside your computer. The processor and memory are particularly sensitive and require an exact supply or as near as possible to one.
an 850 watt supply, with each socket labeled
From the wall
The outlet delivers 120 volts of alternating current. The supply converts it down to steady direct current at 12V, 5V and 3.3V.
Measured in watts
A typical desktop supply is rated between 400 and 750 watts. Add a powerful graphics card and the number climbs quickly.
Laptops too
The heavy block partway along a laptop charger is doing exactly this job, just outside the case instead of inside it.
Power Supplies – Stop Error Maintenance Tip
If your computer starts acting strangely or has repeated stop errors or crash screens, this may be caused by the power supply. The event logs may record these as being due to memory errors, and probably correctly so, but the memory errors could be being caused by an insubstantial power supply to the RAM and/or CPU.
What a stop error is
Windows hits a fault it cannot recover from, so it halts and shows an error screen rather than risk corrupting your files.
Why people say BSOD
The old name is the blue screen of death. Windows 10 still shows blue; since 2025 Windows 11 shows black instead, naming the stop code and the faulty driver.
Why power is a suspect
RAM and the CPU need steady voltage, and a failing supply causes errors that look like faulty memory. Memory can be tested in software; a supply usually has to be swapped to rule it out.
Motherboard
The motherboard gets its name because it is like a mother to all of the other circuit boards.
Found at the bottom of a desktop case or the side of a tower case, the motherboard is the largest circuit board and has many smaller boards plugged into it.
It holds all of the most important parts of the computer.
a motherboard, with its sockets and slots labeled
Where things plug in
The processor drops into the socket in the middle. Memory stands in the row of slots beside it, and cards go in the long PCI Express slots below.
Where storage goes
An M.2 socket takes a bare SSD stick laid flat against the board. The SATA connectors along the edge are for drives that still need a cable.
Where power arrives
A wide 24-pin connector feeds the board itself, and a separate 8-pin one near the top supplies the processor.
Network Interface Card
A network interface card (NIC) is a hardware device that handles an interface to a computer network and allows a network-capable device to join that network. Note the card can be wired or wireless
a network interface card — the socket takes an Ethernet cable
Wired
An Ethernet cable plugs into a square socket. Slower to set up but steadier and quicker than wireless, which is why servers still use it.
Wireless
A Wi-Fi adapter does the same job over radio. On laptops and phones it is a chip soldered to the board, not a card you can remove.
Its own address
Every network card carries a MAC address, a permanent serial number that identifies that one device on a network.
CPU
The brain of a computer is the CPU or Central Processing Unit. It controls information and tells other parts what to do.
The type of CPU in a computer also determines how fast that computer can operate.
A CPU generates lots of heat, so there is usually a small fan nearby to cool it down.
an AMD Ryzen processor — the metal lid carries heat up to the cooler
Cores
A modern processor contains several cores, so it can genuinely work on several tasks at the same time rather than switching between them.
Clock speed
Measured in gigahertz. 3 GHz means three billion cycles every second, and each cycle carries out a step of an instruction.
Heat
All that switching produces heat. The fan and the metal heatsink beneath it exist to carry that heat away before the chip throttles.
GPU
The GPU, or Graphics Processing Unit, is the second processor in a computer. Its job is to work out what every pixel on the screen should look like, many times a second.
A CPU has a handful of powerful cores that take turns on complicated jobs. A GPU has thousands of simple cores that all do the same small calculation at once, which is exactly what drawing millions of pixels needs.
Some computers use graphics built into the processor. Others have a separate graphics card — an expansion card that slides into a long PCI Express slot, so it can be added or upgraded later.
a graphics card — three fans, display sockets down the left edge
Integrated
Built into the processor itself. Costs nothing extra and shares the computer’s RAM. Fine for everyday use.
Dedicated
A card with its own processor and its own memory, called VRAM. Needs the long slot and its own power cables.
Not just graphics
Thousands of identical calculations at once is what AI needs too. That is why AI companies buy GPUs by the thousand.
Cooling: Air
A processor turns electricity into work and into heat. Left alone it would overheat within seconds.
An air cooler sits directly on top of the CPU. A metal block pulls heat out of the chip, a stack of thin fins spreads that heat over a large surface, and a fan blows air through the fins to carry it away.
A graphics card comes with its own cooler already fitted, which is why cards are so much bigger than the board underneath.
an air cooler — two fan units either side of the fins
Thermal paste
A thin layer between the chip and the cooler fills microscopic gaps so heat can cross. Too much works no better than too little.
Case fans
The cooler lifts heat off the chip; case fans move it out of the box. Cool air in at the front, warm air out at the back.
Throttling
If it still runs too hot the processor slows itself down on purpose. A machine that gets sluggish after ten minutes usually needs its dust cleaned out.
Cooling: Liquid
An AIO, or all-in-one cooler, moves the heat somewhere else before getting rid of it.
A pump sits on the processor, liquid carries the heat along two tubes to a radiator bolted to the case, and fans blow it out there. The whole loop is sealed at the factory, so there is nothing to fill and nothing to top up.
Liquid carries far more heat than air for its size, which is what makes the trick work.
an AIO — pump block on the left, tubes, radiator and fans on the right
What it buys you
Room for a much larger radiator than would ever fit on the chip itself, and usually a quieter machine at the same temperature.
What it does not do
It will not make a computer faster. It stops a fast processor from throttling, which is a different thing.
The trade-off
More expensive, and there is a pump that can fail. A sealed loop also wears out eventually, where a heatsink lasts forever.
Have you ever heard the terms
RAM and ROM?
Both are kinds of memory, and the names sound alike. They do almost opposite jobs.
RAM
Random Access Memory
holds what you are working on
ROM
Read Only Memory
holds instructions that stay put
RAM
RAM stands for Random Access Memory. RAM chips will remember what you tell them and can even change to remember new information. But, when the computer is turned off, RAM forgets everything you told it. This is why it is so important to save your work ! If the computer gets turned off, RAM will lose all of your work!
The stick itself is called a DIMM — a Dual In-line Memory Module. The black squares along it are the memory chips.
two DDR5 DIMMs — memory is usually fitted in matched pairs
Why it is fast
The processor reaches any address directly and almost instantly. That is what "random access" in the name means.
Why more helps
Every open tab takes a share. Run out and the computer falls back on the much slower drive, and everything crawls.
DDR5 and its slots
The fifth generation of the design, and it will not fit a DDR4 slot: the notch on the bottom edge is in a different place.
ROM
ROM stands for Read Only Memory. ROM is good at remembering, but cannot change its mind. It holds information that is built into it. ROM is like reading a library book - lots of information is there, but you can't change it (or write in it) (because you never write in a library book). Note: on modern devices this information is held in flash memory, so it can be updated.
a ROM chip — the real thing lives in cartridges, not on a motherboard
Where you meet it
A game cartridge is mask ROM — which is why emulator files are called ROMs. So is a CD-ROM, pressed once at the factory and readable forever.
Inside the processor
Phones and laptops carry a small boot ROM inside the processor itself. It genuinely cannot be rewritten, which is what makes it trustworthy.
What ships on a board
A motherboard has no true ROM chip. It uses flash, which does the ROM job but can still be rewritten — that is what a firmware update is.
RAM and ROM Side by Side
RAM sticks on the left, a ROM chip on the right
RAM
Reads and writes. Loses everything the moment the power goes off. Measured in gigabytes: 8, 16 or 32 in most machines.
ROM
Reads only, in the strict sense. Keeps its contents with the power off. Tiny by comparison, because it only holds startup instructions.
The confusion
The names differ by one letter and both are called memory, which is why students mix them up. The jobs are not similar at all.
UEFI
A very important computer component is the UEFI chip. It is located on the motherboard. UEFI stands for Unified Extensible Firmware Interface. In very simple terms, the UEFI chip wakes up the computer when you turn it on and reminds it what parts it has and what they do.
The chip holds its instructions like a ROM chip would, keeping them with the power off. But it is flash memory, not true ROM, so they can be rewritten — which is how UEFI gets updated.
firmware lives in a small eight-pin chip like this one
The startup check
Before the operating system loads, the chip counts the memory and finds the drives, keyboard and display. This is called the POST.
Then it hands over
It looks through the drives in a set order until it finds an operating system, loads it, and steps out of the way.
It used to be BIOS
UEFI replaced BIOS on essentially every machine after about 2012. Many setup screens still say BIOS, and so do most people. Same thing.
Ports
Ports are the places on the outside of the computer case where you plug in hardware. On the inside of the case, they are connected to the motherboard.
The keyboard, mouse, monitor, and printer all plug into ports. There are also extra ports to plug in extra hardware like joysticks, gamepads, scanners, digital cameras and the like.
USB-C ports on a laptop
One port, many uses
USB replaced a drawer full of different connectors. USB-C carries data, video and power through the same socket.
Video ports
HDMI and DisplayPort carry picture and sound to a screen. On a desktop with a video card, these come off the card rather than the board.
Gone or going
The round PS/2 keyboard and mouse ports, the parallel printer port and the serial port have all disappeared from new machines.
Ports and Cables
The ports are controlled by the motherboard, or by expansion cards plugged into it, and are connected to other components by cables - long, flat bands that contain electrical wiring.
HDMI Cable
HDMI
The one you will meet most often. Carries picture and sound down a single lead, and fits televisions, projectors, monitors and games consoles alike.
DisplayPort
Mostly a computer connector, and usually what a graphics card offers. Handles higher refresh rates, and one port can drive several monitors in a chain.
USB-C
Increasingly carries video as well as data and power, so a laptop can run a monitor, charge itself and move files through one cable.
Storage
Storage holds your files when the power is off. RAM forgets everything the moment you shut down; storage does not.
In most computers built recently the drive is an M.2 SSD — a bare board about the size of a stick of gum, clipped flat onto the motherboard. Older machines use a hard drive with spinning platters instead.
Section 3 covers storage properly: how each kind works, how much it holds, and the other places your files can live.
an M.2 SSD — the drive in most new machines
Not the same as RAM
RAM is the desk you work on and it clears every night. Storage is the filing cabinet, and what you put in stays there.
What is in your machine
A stick clipped to the board, or on older computers a flat drive in a bay with a cable running to it.
Where it plugs in
The M.2 socket on the motherboard, or the SATA connectors along its edge — both labeled on the board photo earlier.
What Am I?
Each one describes a part from this section. Call it out.
1
I turn the electricity from the wall into something the parts can survive.
2
Everything plugs into me. I am the largest board in the case.
3
I do the actual thinking, and I get hot doing it.
4
I have thousands of tiny cores and I work out every pixel you see.
5
I wake the machine and check what parts are attached before the operating system loads.
6
I hold your work while you use it, then forget all of it when the power dies.
7
I am read only, like a library book — lots of information, but you cannot write in me.
8
I remember with the power off, and I have no moving parts at all.