Before opening the case, you must turn the computer off.
Shutdown your operating system as you normally do. On the back of your computer, locate the power switch and turn it off, as shown above.
Some computers do not have a power switch on the back of the computer. If you do not find one, skip to the next step
Unplug the Power Cable
Unplug the power cable that is currently plugged in to the power supply on the back of your computer.
Note: This is an important step! It may seem overly cautious to remove the power cable in addition to powering off the computer normally, but some parts of a computer remain powered on even when the computer seems to be off
Remove All External Cables and Attachments
Remove all cables and other devices attached to to your computer. This will make it much easier to work inside your computer and to move it around as needed.
Remove the Side Panel Retaining Screws
Remove the outermost screws from the case - the ones that are holding the side panels to the rest of the case. You will likely need a phillips-head screwdriver to remove these screws.
Set these screws aside. You will need to use them to secure the side panels to the case again when you are through working inside your computer.
Note: Take care not to remove the screws that are securing the power supply to the case. These screws are more inset than the case retaining screws and may cause the power supply to fall into the computer, possibly causing damage.
Remove the Case Side PanelThe case side panel can now be removed.
Sometimes the panel can simply be lifted off while other times it may be
attached to the case in a slide-lock manner. No matter the mechanism,
you should be able to easily jar the panel loose.