Dell Dimension 4500S Manual 

Also see for Dimension 4500S: Owner's manual

1. Shut down the computer.2. Turn off any attached devices and disconnect them from their electrical outlets.3. Disconnect the computer power cable from the wall outlet, and then press the power button to ground the system board.4. Remove the computer stand, if it is attached.5. Locate the two release buttons shown in the illustration. Then, press the two release buttons as you lift the cover.Raise the back of the cover, and pivot it toward the front of the computer.Looking Inside Your ComputerCAUTION: Before you begin any of the procedures in this section, follow the "Safety Instructions."CAUTION: To guard against electrical shock, always unplug your computer from the electrical outlet before opening the cover.NOTICE: To disconnect a network cable, first unplug the cable from your computer and then unplug it from the network wall jack.NOTICE: Ensure that there is sufficient space to support the open cover—at least 30 cm (1 ft) of desk top space.NOTICE: Open the cover slowly to ensure that you do not damage any cables.CAUTION: Before you begin any of the procedures in this section, follow the "Safety Instructions."CAUTION: To guard against electrical shock, always unplug your computer from the electrical outlet before opening the cover.NOTICE: Be careful when you open the computer cover to ensure that you do not inadvertently disconnect cables from the system board.