Dell OptiPlex 990 (Early 2011) - Manual (Page 71)

• If available, install working memory of the same type
into your computer.
LED
Power Button
Problem Description Memory modules are detected, but a memory
configuration or compatibility error has occurred.
Troubleshooting Steps • Ensure that no special requirements for memory
module/connector placement exist.
• Ensure that the memory you are using is supported
by your computer.
LED
Power Button
Problem Description A possible expansion card failure has occurred.
Troubleshooting
Steps
• Determine if a conflict exists by removing an
expansion card (not a graphics card) and restarting
the computer.
• If the problem persists, reinstall the card you
removed, then remove a different card and restart
the computer.
• Repeat this process for each expansion card
installed. If the computer starts normally,
troubleshoot the last card removed from the
computer for resource conflicts.
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