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Understanding the Internal and External Components of a Computer


#disassemblingacpu #btec #ICT #unit14 #dell755 How to Disassembly Dell CPU||Unit 14 Btec ICT level 2

If you’re diving into Unit 14 of BTEC ICT, you’ll need to get familiar with the different internal and external components of a computer. In this blog post, we’ll break down each part, show you how to disassemble a CPU using a Dell Optiplex 755 as an example, and explain how each internal component connects to the motherboard.



💻 External Components of a Computer

Let’s start with what you can see on the outside of a typical desktop computer:

  • Monitor – Displays the user interface and applications.

  • Keyboard – Inputs letters, numbers, and commands.

  • Mouse – Allows for navigation and selection.

  • Speakers – Outputs sound from the system.

  • Printer – Used to produce hard copies of documents.

  • External Drives – USB drives or external HDDs for storage.

  • Webcam & Microphone – Useful for video calls and recordings.

  • Network Cable (Ethernet) – Connects the system to the internet or LAN.

These are plug-and-play devices, and most connect via USB or HDMI ports found at the back or sides of the computer.



🧠 Internal Components of a Computer

Now for the exciting part—inside the case. These are the components that do the heavy lifting.

1. CPU (Central Processing Unit)

This is the brain of the computer. It processes all the instructions from programs and applications. It's seated directly onto the motherboard in a special socket.

2. Memory (RAM - Random Access Memory)

RAM is your temporary memory. It allows your computer to work on multiple tasks at once. You’ll find long, thin RAM sticks that slide into dedicated RAM slots on the motherboard.

3. GPU (Graphics Processing Unit)

This is either integrated with the CPU or installed as a dedicated graphics card. It processes everything visual—games, videos, design software. It slots into the PCIe (Peripheral Component Interconnect Express) slot on the motherboard.

4. Cooling Fan and Heat Sink

These prevent your CPU and GPU from overheating. The CPU cooler usually sits on top of the processor, connected via a clip or screws, with a power cable that connects to the motherboard's fan header.

5. Hard Drive (HDD) or SSD

This is where all your data is stored. HDDs are usually mounted in drive bays and connected to the motherboard via SATA cables.

6. Power Supply Unit (PSU)

Converts electricity from your wall socket into usable power for your computer. Cables from the PSU connect to the motherboard, CPU, and other components.



🔧 How to Disassemble a Dell Optiplex 755

⚠️ Safety First: Turn off the computer, unplug it, and ground yourself to avoid static damage.

  1. Remove the Side Panel

    • Use a screwdriver or pull the latch (depending on the model).

    • Carefully slide off the panel.

  2. Locate and Remove the Cooling Fan

    • Disconnect the fan cable from the motherboard.

    • Unscrew or unclip the fan from the CPU socket.

  3. Remove the CPU

    • Lift the metal retention bracket.

    • Gently lift the CPU out of the socket (do not force it).

  4. Remove the RAM

    • Press down on the clips at either end of the RAM slots.

    • Gently pull the RAM sticks upwards.

  5. Remove the GPU (if present)

    • Unscrew it from the case.

    • Press the small plastic lever at the end of the PCIe slot and pull the card out carefully.

  6. Disconnect the HDD or SSD

    • Unplug the SATA data and power cables.

    • Unscrew and slide the drive out.

  7. Disconnect PSU Connections

    • Remove the 24-pin and 8-pin power connectors from the motherboard.

    • Disconnect cables going to drives and fans.

🛠️ Reconnecting Components to the Motherboard

  • CPU → Align the triangle mark on the CPU with the socket, gently place it in, and secure the bracket.

  • RAM → Slide into the RAM slots until the clips snap back into place.

  • GPU → Push firmly into the PCIe slot until it clicks, then screw it in.

  • Cooling Fan → Place on top of the CPU, secure it, and plug the fan cable into the CPU_FAN header.

  • Storage Drive → Slide into the bay, connect SATA cable to the drive and motherboard, then connect power from PSU.

  • Power Supply → Plug in all necessary cables:

    • 24-pin main motherboard power

    • 8-pin CPU power

    • GPU power (if needed)

    • SATA power to drives

🧩 Final Tips

  • Always take pictures before you disassemble, so you can follow them when reconnecting.

  • Handle components with care and avoid touching metal pins or circuits.

  • Label your cables if it’s your first time working inside a PC.





 
 
 

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