Dell OptiPlex 780 - Manual (Page 24)

4-4-2 Failure to decompress code to shadowed memory
4-4-3 Math-coprocessor test failure
4-4-4 Cache test failure
Diagnostic Lights
To help troubleshoot a problem, your computer has four lights labeled 1, 2, 3, and 4 on the bank panel. When the
computer starts normally, the lights flash before turning off. If the computer malfunctions, the sequence of the lights help
to identify the problem.
NOTE: After the computer completes POST, all four lights turn off before booting to the operating system.
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.
If the problem persists, contact Dell.
A possible processor
failure has occurred.
Reseat the processor (see Processor information for your computer).
If the problem persists, contact Dell.
Memory modules are
detected, but a
memory failure has
occurred.
If two or more memory modules are installed, remove the modules,
then reinstall one module and restart the computer. If the computer
starts normally, continue to install additional memory modules (one at
a time) until you have identified a faulty module or reinstalled all
modules without error.
If available, install working memory of the same type into your
computer.
If the problem persists, contact Dell.
A possible graphics
card failure has
occurred.
Reseat any installed graphics cards.
If available, install a working graphics card into your computer.
If the problem persists, contact Dell .
A possible floppy drive
or hard drive failure
has occurred.
Reseat all power and data cables.
A possible USB failure
has occurred.
Reinstall all USB devices and check all cable connections.
No memory modules
are detected.
If two or more memory modules are installed, remove the modules,
then reinstall one module and restart the computer. If the computer
starts normally, continue to install additional memory modules (one at
a time) until you have identified a faulty module or reinstalled all
modules without error.
If available, install working memory of the same type into your
computer.
If the problem persists, contact Dell.
Memory modules are
detected, but a
memory configuration
or compatibility error
has occurred.
Ensure that no special requirements for memory module/connector
placement exist.
Ensure that the memory you are using is supported by your computer
(see the "Specifications" section for your computer).
If the problem persists, contact Dell.
A possible expansion
card failure has
occurred.
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.