After Working Inside Your Computer - Dell OptiPlex 990 Desktop Service Manual

Click Start
menu as shown below, and then click Shut Down.
– In Windows XP:
Click Start → Turn Off Computer → Turn Off . The computer turns off after
the operating system shutdown process is complete.
2. Ensure that the computer and all attached devices are turned off. If your computer
and attached devices did not automatically turn off when you shut down your
operating system, press and hold the power button for about 6 seconds to turn them
off.

After Working Inside Your Computer

After you complete any replacement procedure, ensure you connect any external
devices, cards, and cables before turning on your computer.
1. Replace the cover.
CAUTION: To connect a network cable, first plug the cable into the network device
and then plug it into the computer.
2. Connect any telephone or network cables to your computer.
3. Connect your computer and all attached devices to their electrical outlets.
4. Turn on your computer.
5. Verify that the computer works correctly by running the Dell Diagnostics.
, then click the arrow in the lower-right corner of the Start
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