The case of your computer houses all the components that it may have, protects them from damage and allows the air flow to keep everything cool. Opening it will allow you to clean up excess dust and replace or install new components. You can access many more components on a desktop computer than on a laptop, in which you normally only have access to the RAM and the hard drive.
Steps
Part 1 of 3: Open a desktop computer

Step 1. Gather your tools
Access to most housings only requires a screwdriver. Some housings use thumb screws, but a screwdriver can still loosen one that is extremely tight.
- The most common screw is the 6-32 screw, which you can remove using a standard # 2 Phillips screwdriver.
- The second most common screw is the M3. This is a little smaller than the 6-32, but you can still remove it with a # 2 Phillips screwdriver.
- If you want to clean the inside of the case, you probably need compressed air and one small vacuum cleaner.
- A antistatic wristband It can be helpful for grounding yourself while working inside your computer, but you can also do it without using one.

Step 2. Turn off the computer
Use the shutdown feature of the operating system to shut down the computer.

Step 3. Disconnect all the cables at the back of the computer
If you don't think you'll be able to remember where everything connects when you do it again, take a picture or draw a diagram.

Step 4. Identify the Input / Output (I / O) panel
This is located on the back of the computer and contains a variety of different connectors, including Ethernet, speakers, USB, monitor, and more. Knowing its location will allow you to orient the case when you place it on the table.

Step 5. Place the enclosure on your work surface with the I / O panel laying as close to the surface as possible
This will allow you to remove the correct panel on the computer and thus gain access to the internal components.
Avoid resting the case on the carpet while working inside

Step 6. Find the screws along the back of the case
You should see two or three screws along the top edge on the back of the case, which hold the side panel in place. If you remove them, you can remove the side panel.
Many of the enthusiast range housings and some that come from major manufacturers will use different panel mechanisms. Some will use thumb screws that you can remove by hand, while others will have a simple latch without any screws. If you are having difficulty figuring out how to remove or open the side panel of your case, research your computer or case model online

Step 7. Ground yourself before touching any component
Electrostatic discharge can cause considerable damage to your computer's components without even noticing it. Make sure you ground yourself properly when attaching the antistatic strap to the metal of the case or touching a metal tap.
Click here for more details on how to properly ground yourself

Step 8. Clean your computer while it is open
The computer collects dust surprisingly quickly, which can lead to overheating, poor performance, and hardware failure. Every time you open your computer, take a few minutes to make sure dust is not a problem.
Click here for more details on how to clean a computer
Part 2 of 3: Identify the Components of a Desktop Computer

Step 1. Identify the motherboard
This is the large logic board that all other components are connected to. The average motherboard has a socket, PCI slots for graphics and expansion cards, slots for RAM, and SATA ports for hard drives and optical drives.
Click here for detailed instructions on how to install or replace a motherboard

Step 2. Identify the processor
Usually, you won't be able to see the processor because it is covered by a heat sink. It is usually located in the middle of the motherboard, closer to the top than to the bottom.
- Click here for detailed instructions on installing a processor.
- Click here for detailed instructions on applying thermal paste and installing a heat sink.

Step 3. Identify the RAM
RAM modules are long and short, and the slots are generally located very close to the processor socket. The RAM modules can fit partially or completely in the sockets.
Click here for detailed instructions on installing new RAM

Step 4. Identify the graphics card
If your computer has a graphics card installed, it will be in the PCI slot closest to the processor called the PCI-E slot. The PCI slots are generally located in the lower half of the motherboard and are aligned with the compartment covers at the rear of the chassis.
- Click here for detailed instructions on installing a new video card.
- Click here for detailed instructions on installing PCI expansion cards.

Step 5. Identify the computer's power source
Depending on your case, the power supply can be located on the top or bottom, along the back. It is a large box that provides power to all the components of the computer. You can track the power cables to see that all the components are connected.
Click here for detailed instructions on installing a new power supply

Step 6. Find the hard drives
Hard drives are usually installed in the bays attached to the front of the case and are connected to the motherboard via SATA cables (IDE cables are used in older computers, which are wide and flat). They are also connected to the power supply via SATA connectors (older drives use Molex connectors).
Click here for detailed instructions on installing a new hard drive

Step 7. Identify the optical drive (s)
They are often located just above hard drives. They are larger than the typical hard drive and protrude towards the front of the case so that they can be accessed. Like hard drives, all modern optical drives use SATA connectors.
Click here for detailed instructions on installing a DVD drive

Step 8. Identify the fans
Most computers will have multiple fans installed. There may be one or more fans in the case, as well as one in the processor. These fans are connected to the motherboard and can also be connected to the power supply.
Click here for detailed instructions on installing a new computer fan
Part 3 of 3: Open a laptop

Step 1. Gather your supplies
Laptops use much smaller screws than desktop computers, so you will need a smaller screwdriver. The one most frequently used in laptops is the Phillips # 0.
- If you want to clean the inside of the laptop, you will need a can of compressed air.

Step 2. Turn off the laptop
Use the shutdown feature of the operating system to shut down the laptop.

Step 3. Disconnect all cables
These include the power adapter and all USB devices, headphones, or other peripherals.

Step 4. Flip the laptop over on the work surface
You will probably see one or more panels that you can remove. Compared to desktop computers, laptops have much less access to components. This is because it is not possible to replace most of the hardware in a laptop without having extensive knowledge of soldering.

Step 5. Remove the battery
This will avoid accidentally turning on your laptop while working on it.

Step 6. Remove the screws from the panels you want to open
Perhaps there are one or more panels that give you access to the components you want to replace. Most laptops will allow you to access the hard drive compartment and RAM.
- Click here for detailed instructions for installing a new laptop RAM.
- Click here for detailed instructions on installing a new laptop hard drive.