Dell OptiPlex 390 (Mid 2011) - Manual (Page 8)

To avoid damaging your computer, perform the following steps before you begin
working inside the computer.
1. Ensure that your work surface is flat and clean to prevent the computer
cover from being scratched.
2. Turn off your computer (see Turning Off Your Computer).
CAUTION: To disconnect a network cable, first unplug the cable from your
computer and then unplug the cable from the network device.
3. Disconnect all network cables from the computer.
4. Disconnect your computer and all attached devices from their electrical
outlets.
5. Press and hold the power button while the computer is unplugged to
ground the system board.
6. Remove the cover.
CAUTION: Before touching anything inside your computer, ground yourself by
touching an unpainted metal surface, such as the metal at the back of the
computer. While you work, periodically touch an unpainted metal surface to
dissipate static electricity, which could harm internal components.
Recommended Tools
The procedures in this document may require the following tools:
• Small flat-blade screwdriver
• Phillips screwdriver
• Small plastic scribe
• Flash BIOS update program media
Turning Off Your Computer
CAUTION: To avoid losing data, save and close all open files and exit all open
programs before you turn off your computer.
1. Shut down the operating system:
• In Windows 7:
Click Start , then click Shut Down.
• In Windows Vista:
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