Diagnostic Lights - Dell OptiPlex 755 User Manual

Solid green power light and no
beep code but the computer
locks up during POST
Diagnostic Lights
CAUTION: Before you begin any of the procedures in this section, follow the safety instructions in the Product Information Guide.
To help troubleshoot a problem, your computer has four lights labeled 1, 2, 3, and 4 on the front 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
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.
A possible processor failure has
occurred.
Memory modules are detected,
but a memory failure has
occurred.
A possible graphics card failure
has occurred.
A possible floppy drive or hard
drive failure has occurred.
A possible USB failure has
occurred.
No memory modules are
detected.
Memory modules are detected,
but a memory configuration or
compatibility error has occurred.
A possible expansion card failure
has occurred.
Another failure has occurred.
An integrated system board device may be faulty.
Suggested Resolution
Plug the computer into a working electrical outlet (see
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If the problem persists, contact Dell (see
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Reseat the processor (see Processor information for your computer).
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If the problem persists, contact Dell (see
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If two or more memory modules are installed, remove the modules (see
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reinstall one module (see
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 (see
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If the problem persists, contact Dell (see
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Reseat any installed graphics cards (see the "Cards" section for your computer).
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If available, install a working graphics card into your computer.
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If the problem persists, contact Dell (see
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Reseat all power and data cables.
Reinstall all USB devices and check all cable connections.
If two or more memory modules are installed, remove the modules (see
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reinstall one module (see
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 (see
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If the problem persists, contact Dell (see
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Ensure that no special requirements for memory module/connector placement exist (see
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Memory).
Ensure that the memory you are using is supported by your computer (see the "Specifications"
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section for your computer).
If the problem persists, contact Dell (see
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1. Determine if a conflict exists by removing an expansion card (not a graphics card) and restarting
the computer (see the "Cards" section for your computer).
2. If the problem persists, reinstall the card you removed, then remove a different card and restart
the computer.
3. Repeat this process for each expansion card installed. If the computer starts normally,
troubleshoot the last card removed from the computer for resource conflicts (see
Software and Hardware Problems in the Microsoft® Windows® XP and Microsoft Windows Vista®
Operating
4. If the problem persists, contact Dell (see
Ensure that all hard drive and optical drive cables are properly connected to the system board
l
(see the "System Board Components" section for your computer).
If there is an error message on the screen identifying a problem with a device (such as the
l
floppy drive or hard drive), check the device to make sure it is functioning properly.
If the operating system is attempting to boot from a device (such as the floppy drive or optical
l
drive), check system setup (see
devices installed on your computer.
If the problem persists, contact Dell (see
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See Video and Monitor
Check the diagnostic lights to see if the specific problem is identified
(see Diagnostic
for technical assistance (see
Contacting
Contacting
Installing Memory) and restart the computer. If the computer starts
Contacting
Contacting
Installing Memory) and restart the computer. If the computer starts
Contacting
Contacting
Systems).
Contacting
System Setup) to ensure the boot sequence is correct for the
Contacting
Problems.
Lights). If the problem is not identified, contact Dell
Contacting Dell).
Power Problems).
Dell).
Dell).
Removing
Installing
Dell).
Dell).
Removing
Installing
Dell).
Dell).
Dell).
Dell).
Memory), then
Memory).
Memory), then
Memory).
Troubleshooting