Dell OptiPlex 990 (Early 2011) - Manual (Page 8)

CAUTION: When you disconnect a cable, pull on its connector or on its pull-tab, not
on the cable itself. Some cables have connectors with locking tabs; if you are
disconnecting this type of cable, press in on the locking tabs before you disconnect
the cable. As you pull connectors apart, keep them evenly aligned to avoid bending
any connector pins. Also, before you connect a cable, ensure that both connectors
are correctly oriented and aligned.
NOTE: The color of your computer and certain components may appear differently
than shown in this document.
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
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