Dell OptiPlex systems have a long history of built in diagnostic indicators. These can be audible beeps, power buttons that display different states and colours, specific diagnostics LEDs or a combination of them all, in order to indicate at which point during the Power On Self Test (POST) a system is having issues.
The following article is a reference guide to the codes available on each model and what those codes actually mean. These change through the various models and years. These indicators are merely a starting point to narrow down any troubleshooting you will carry out to identify the cause of your current issue. You can use this as a starting point to narrow down the proper troubleshooting guide you will need or you can contact technical support for further help and they will be looking for these indicators as well.

Note: For all the tables below, please remember that the diagnostic LEDs only serve as an indicator of the progress through the POST process. These LEDs do not indicate the problem that caused the POST routine to stop.

1. Diagnostic LEDs for the OptiPlex series (Prior to 2005)
This series of systems had a block of A, B, C, D LEDs on the back of the chassis that lit up in Green and Amber. I’ve included a table below with what these indicated. These models were readily identifiable by the rounded fronts and clamshell assembly.
OptiPlex Prior to 2005

 

 

 

Diagnostic LEDs

CPU configuration activity or failure; CPU Cache failure

LED
Pattern
State
Name
State
Description
Suggested Resolution
No Pattern Visible
Off
System POST complete – LED time-out has occurred
  • If the LEDs came on and then went off, look at troubleshooting the display and the operating system.
  • If the LEDs never came on at any point then look into a power issue.
ABCD
RCM
BIOS checksum failure – Recovery mode
  • Reset the BIOS and clear the NVRAM
  • If this occurred after windows updates, check your startup wasn’t corrupted.
ABCD
CPU
  • Disconnect all external peripherals and configure PC down to PSU, Motherboard and CPU
  • If fault continues contact your technical support
  • If fault stops, plug disconnected parts back one at a time until fault re-occurs. Contact your technical support to take this further.
ABCD
MEM
Memory subsystem configuration activity or failure
  • Remove all memory from PC, does the LED code change?
  • If it doesn’t contact your technical support
  • If it does add the memory modules back one at a time until the fault re-occurs, test that module in another slot and contact your technical support
ABCD
PCI
PCI device configuration or failure
  • Remove all external peripherals and all internal PCI devices
  • If fault continues contact your technical support
  • If fault stops, add parts back one at a time until fault re-occurs and contact your technical support
ABCD
VID
Video subsystem configuration or failure
  • Ensure the video cable is connected to the correct port
  • Reseat any add in graphics cards
  • If fault continues, remove any add in graphics cards and test with known good monitor and video cable
  • Contact your technical support once you know which part the fault follows
ABCD
STO
Storage device configuration or failure
  • Reseat the cables from the HDDs to the motherboard
  • If fault continues try substituting a known good HDD into the system and contact your technical support
ABCD
USB
USB subsystem configuration activity or failure
  • Remove all external peripherals and any internal CRUs
  • If LEDs change, add parts back one at a time until fault re-occurs and contact your technical support
  • If fault remains the same with parts removed, contact your technical support
ABCD
No memory detected
  • Reseat all memory modules
  • If fault continues, try the memory in different slots and contact your technical support
ABCD
MBF
Fatal system board failure detected
  • Contact your technical support
ABCD
Memory is detected, configuration or compatibility error
  • Reset the BIOS and clear the NVRAM and any previous errors
  • Remove all memory from PC, (This includes any Graphics cards.) does the LED code change?
  • If it doesn’t contact your technical support
  • If it does add the parts back one at a time until the fault re-occurs, test that part in another slot and contact your technical support
ABCD
PRV
Indicates system activity preceding video initialization
  • Remove all external peripherals and any internal CRUs
  • If LEDs change, add parts back one at a time until fault re-occurs and contact your technical support
  • If fault remains the same with parts removed, contact your technical support
ABCD
CFG
System resource configuration
  • Reset the BIOS and clear the NVRAM and any previous errors
  • Remove all external peripherals
  • If LEDs change, add parts back one at a time until fault re-occurs and contact your technical support
  • If fault remains the same with parts removed, contact your technical support
ABCD
Reserved
  • Reserved
ABCD
POV
POST complete — Onscreen error message
  • Troubleshoot as per the error message onscreen
ABCD
STD
POST complete — OS hand-off complete
  • The Power On Self Test has passed all checks
  • Troubleshoot the HDD and the Operating System



2. Diagnostic LEDs for the OptiPlex series (2005 to 2009)

This series had a combination of Power button LED states and the A, B, C, B, block was replaced with 1, 2, 3, 4, instead. The diagnostics LEDs moved from the rear of the chassis to the front under the audio ports. You could identify these models by their flat black front face and grey side panels/lids.
OptiPlex 2005-2009

 

Power LEDs

Off
Blinking Amber
Solid Amber
Solid Green
Blinking Green
Off
Blinking Amber
Solid Amber
Solid Green
Blinking Green

 

Diagnostics LEDs

LED Pattern
(1 2 3 4)
LED
Pattern
State
Name
State
Description
Suggested Resolution
Off
Off
System POST complete — LED time-out has occurred
  • If the LEDs came on and then went off, look at troubleshooting the display and the operating system.
  • If the LEDs never came on at any point then look into a power issue.
4
RCM
BIOS checksum failure — Recovery mode
  • Reset the BIOS and clear the NVRAM
  • If this occurred after windows updates, check your startup wsn’t corrupted.
3
CPU
CPU configuration activity or failure; CPU Cache failure
  • Disconnect all external peripherals and configure PC down to PSU, Motherboard and CPU
  • If fault continues contact your technical support
  • If fault stops, plug disconnected parts back one at a time until fault re-occurs. Contact your technical support to take this further.
34
MEM
Memory subsystem configuration activity or failure
  • Remove all memory from PC, does the LED code change?
  • If it doesn’t contact your technical support
  • If it does add the memory modules back one at a time until the fault re-occurs, test that module in another slot and contact your technical support
2
PCI
PCI device configuration or failure
  • Remove all external peripherals and all internal PCI devices
  • If fault continues contact your technical support
  • If fault stops, add parts back one at a time until fault re-occurs and contact your technical support
2 4
VID
Video subsystem configuration or failure
  • Ensure the video cable is connected to the correct port
  • Reseat any add in graphics cards
  • If fault continues, remove any add in graphics cards and test with known good monitor and video cable
  • Contact your technical support once you know which part the fault follows
23
STO
Storage device configuration or failure
  • Reseat the cables from the HDDs to the motherboard
  • If fault continues try substituting a known good HDD into the system and contact your technical support
234

USB
USB subsystem configuration activity or failure
  • Remove all external peripherals and any internal CRUs
  • If LEDs change, add parts back one at a time until fault re-occurs and contact your technical support
  • If fault remains the same with parts removed, contact your technical support
1
No memory detected
  • Reseat all memory modules
  • If fault continues, try the memory in different slots and contact your technical support
1 4
MBF
Fatal system board failure detected
  • Contact your technical support
1 3
Memory is detected, configuration or compatibility error
  • Reset the BIOS and clear the NVRAM and any previous errors
  • Remove all memory from PC, (This includes any Graphics cards.) does the LED code change?
  • If it doesn’t contact your technical support
  • If it does add the parts back one at a time until the fault re-occurs, test that part in another slot and contact your technical support
1 34
PRV
Indicates system activity preceding video initialization
  • Remove all external peripherals and any internal CRUs
  • If LEDs change, add parts back one at a time until fault re-occurs and contact your technical support
  • If fault remains the same with parts removed, contact your technical support
12
CFG
System resource configuration
  • Reset the BIOS and clear the NVRAM and any previous errors
  • Remove all external peripherals
  • If LEDs change, add parts back one at a time until fault re-occurs and contact your technical support
  • If fault remains the same with parts removed, contact your technical support
12 4
Reserved
  • Reserved
123
POV
POST complete — Onscreen error message
  • Troubleshoot as per the error message onscreen
1234
STD
POST complete — OS hand-off complete
  • The Power On Self Test has passed all checks
  • Troubleshoot the HDD and the Operating System


3. Diagnostic LEDs for the Opt
iPlex series (2009 to 2012)

With this series, the diagnostic LEDs changed to include a combination of the Power button LED state and the diagnostic LED indicators. The Diagnostic LEDs remain 1, 2, 3, 4, and placed on the front of the unit. You could identify these system by their flat black and grey front face.
OptiPlex 2009-2012

Power LED and Diagnostic LEDs

Light Pattern
Problem
Description
Suggested Resolution
Diagnostic LEDs
Power
Button LED
The computer is either turned off or not receiving power.
  • Reseat the power cable in the power connector on the back of the computer and the electrical outlet.
  • Bypass power strips, power extension cables, and other power protection devices to verify that the computer turns on properly.
  • Ensure that any power strips being used are plugged into an electrical outlet and are turned on.
  • Ensure that the electrical outlet is working by testing it with another device, such as a lamp.
  • Ensure that the main power cable and front panel cable are securely connected to the system board.
A possible system board failure has occurred.
  • Unplug the computer. Allow one minute for the power to drain. Plug the computer into a working electrical outlet and press the power button.

Blinking
A possible system board, power supply, or peripheral failure has occurred.
  • Power off computer, leaving the computer plugged in. Press and hold the power supply test button on the rear of the power supply unit. If the LED next to the switch illuminates, the problem may be with your system board.
  • If the LED next to the switch does not illuminate, disconnect all internal and external peripherals, and press and hold the power supply test button.If it illuminates, there could be a problem with a peripheral.
  • If the LED still does not illuminate, remove the PSU connections from the system board, then press and hold the power supply button. If it illuminates, there could be a problem with the system board.
  • If the LED still does not illuminate, the problem is probably with the power supply.
No CPU present.
  • Reinstall the CPU and restart the system. If the computer still fails to boot, inspect the CPU socket for damage.
Memory modules are detected, but a memory power 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 only one memory module is installed, try moving it to a different DIMM connector and restart the computer.
  • If available, install verified working memory of the same type into your computer.
A possible CPU or system board failure has occurred.
  • Replace the CPU with a known good CPU. If the computer still fails to boot, inspect the CPU socket for damage.
BIOS may be corrupt or missing.
  • The computer hardware is operating normally but the BIOS may be corrupt or missing.
A possible system board failure has occurred.
  • Remove all peripheral cards from the PCI and PCI-E slots and restart the computer. If the computer boots, add the peripheral cards back one by one until you find the bad one.
Power connector not installed properly.
  • Reseat the 2×2 power connector from the power supply unit.
Possible peripheral card or system board failure has occurred.
  • Remove all peripheral cards from the PCI and PCI-E slots and restart the computer. If the computer boots, add the peripheral cards back one by one until you find the bad one.
A possible system board failure has occurred.
  • Disconnect all internal and external peripherals, and restart the computer. If the computer boots, add the peripheral cards back one by one until you find the bad one.
  • If the problem persists, the system board is probably bad.
A possible coin cell battery failure has occurred.
  • Remove the coin cell battery for one minute, reinstall the battery, and restart.
The computer is in a normal on condition. The diagnostic lights are not lit after the computer successfully boots to the operating
system.
  • Ensure that the display is connected and powered on.
A possible processor failure has occurred.
  • Reseat the processor.
Memory modules are detected, but a memory failure has occurred.
  • If two or more memory modules are installed, remove the modules (see your service manual), then reinstall one module (see your service manual 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.
A possible graphics card failure has occurred.
  • Reseat any installed graphics cards.
  • If available, install a working graphics card into your computer.
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 (see your service manual), then reinstall one module (see your service manual) 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.
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.
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.
  • Repeat this process for each expansion card installed. If the computer starts normally, troubleshoot the last card removed from the computer for resource conflicts.
A possible system board resource and/or hardware failure has occurred.
  • Clear CMOS.
  • Disconnect all internal and external peripherals, and restart the computer. If the computer boots, add the peripheral cards back one by one until you find the bad one.
  • If the problem persists, the system board / system board component is probably bad.
Another failure has occurred.
  • Ensure that all hard drive and optical drive cables are properly connected to the system board.
  • If there is an error message on the screen identifying a problem with a device (such as the 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 drive), check system setup to ensure the boot sequence is correct for the devices installed on your computer.

4. Diagnostic LEDs for the OptiPlex series (2012 to Present)
With the latest series, the diagnostics indicator LEDs have been removed. Instead the Power Button state now gives a blink and colour shift pattern to indicate where its had a problem. You can identify these systems by the fact that there is no Diagnostics LED block on the front of the unit.

Note : If you have an OptiPlex AIO (All In One) System. Please use the reference tables below.


Diagnostic Indicator Table

5. OptiPlex audible Beep codes
In addition to the various types of diagnostics LEDs, there are a number of audible beep codes across all the models of these systems.
These codes are recognised across manufacturers and have remained the same for some time.
The key to these codes are displayed in the table below.

Beep Codes Table

Diagnostic Beep Codes
Code
Cause
Suggested Resolution
1-1-2
Microprocessor register failure
Contact Technical Support
1-1-3
NVRAM
Run the Dell Diagnostics
1-1-4

ROM BIOS checksum failure
Run the Dell Diagnostics
1-2-1
Programmable interval timer
Run the Dell Diagnostics
1-2-2
DMA initialization failure
Run the Dell Diagnostics
1-2-3
DMA page register read/write failure
Run the Dell Diagnostics
1-3-1 through 2-4-4
DIMMs not being properly identified or used
Troubleshoot the memory modules and the memory slots.
3-1-1
Slave DMA register failure
Run the Dell Diagnostics
3-1-2
Master DMA register failure
Run the Dell Diagnostics
3-1-3
Master interrupt mask register failure
Contact Technical Support
3-1-4
Slave interrupt mask register failure
Contact Technical Support
3-2-2
Interrupt vector loading failure
Contact Technical Support
3-2-4
Keyboard Controller test failure
Run the Dell Diagnostics
3-3-1
NVRAM power loss
Run the Dell Diagnostics
3-3-2
NVRAM configuration
Run the Dell Diagnostics
3-3-4
Video Memory Test failure
Run the Dell Diagnostics
3-4-1
Screen initialization failure
Run the Dell Diagnostics
3-4-2
Screen retrace failure
Run the Dell Diagnostics
3-4-3
Search for video ROM failure
Run the Dell Diagnostics
4-2-1
No time tick
Contact Technical Support
4-2-2
Shutdown failure
Contact Technical Support
4-2-3
Gate A20 failure
Contact Technical Support
4-2-4
Unexpected interrupt in protected mode

Contact Technical Support
4-3-1
Memory failure above address 0FFFFh
Run the Dell Diagnostics
4-3-3
Timer-chip counter 2 failure
Contact Technical Support
4-3-4
Time-of-day clock stopped
Contact Technical Support
4-4-1
Serial or parallel port test failure
Run the Dell Diagnostics
4-4-2
Failure to decompress code to shadowed memory
Run the Dell Diagnostics
4-4-3
Math coprocessor test failure
Run the Dell Diagnostics
4-4-4
Cache test failure
Run the Dell Diagnostics

 

MY EXPERIENCE
A solid green light means the computer is operating normally.
A solid yellow light indicates the power supply is operating normally but the computer is not processing data. This could mean there is a problem with the CPu or another component on the motherboard.

A blinking yellow light indicates the power supply is receiving power from the wall, but not functioning properly. This generally means the power supply itself is bad and should be tested or replaced.
A blinking green light means the computer is in standby mode.
Source: Dell support

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