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32 Quick Reference Guide
Diagnostic Lights
CAUTION: Before you begin any of the procedures in this section, follow the safety instructions in the
Product Information Guide.
To help you troubleshoot a problem, your computer has four lights labeled "1," "2," "3," and "4" on the
front or back panel. The lights can be "off" or green. When the computer starts normally, the patterns or
codes on the lights change as the boot process completes. If the POST portion of system boot completes
successfully, all four lights display solid green for a short time, and then turn off. If the computer
malfunctions during the POST process, the pattern displayed on the LEDs may help identify where in
the process the computer halted. If the computer malfunctions after a successful POST, the diagnostic
lights do not indicate the cause of the problem.
NOTE: The orientation of the diagnostic lights may vary depending on the system type. The diagnostic lights can
appear either vertical or horizontal.
Light Pattern Problem Description Suggested Resolution
The computer is in a normal "off" condition,
or a possible pre-BIOS failure has occurred.
The diagnostic lights are not lit after the
computer successfully boots to the operating
system.
Plug the computer into a working electrical
outlet and press the power button.
A possible BIOS failure has occurred; the
computer is in the recovery mode.
Run the BIOS Recovery utility, wait for
recovery completion, and then restart the
computer.
A possible processor failure has occurred. Reinstall the processor and restart the
computer.
For information on reinstalling the
processor, see your online
User’s Guide
.