A Reference Guide to the Precision Workstation Diagnostic Indicators

The Power Button state now gives a new blink and color shift pattern. It uses both Amber, and White power LED flashes to indicate where it has a problem. You can identify these desktops by the fact that there is no Diagnostics LED block on the front of the unit.

Power Button LEDs

Power Button LED	State	Description
	Off	The power is Off. LED is blank.
	Blinking Amber	Initial State of LED when you switch it on. See the table below for Blinking Amber pattern diagnostic suggestions and possible failures.
	Solid Amber	The second state of the LED when you switch it on indicates that the POWER_GOOD signal is active. It also indicates that the power supply is fine.
	Blinking White	The desktop is in a low-power state, either S1 or S3. This does not indicate a fault condition.
	Solid White	The device is in the S0 state. This is the normal power states of a functioning machine. The BIOS turns the LED to this state to indicate it has started fetching op-codes.

Diagnostic Indicator Table

With this series, the diagnostics indicator LEDs have been removed. Instead the Power Button state now gives a blink and color shift pattern to indicate where it had a problem. You can identify these desktops by the fact that there is no Diagnostics LED block on the front of the unit.

Power Button LEDs

Power Button LED	State	Description
	Off	The power is Off. LED is blank.
	Blinking Amber	Initial State of the LED at switching the device on. See the table below for Blinking Amber pattern diagnostic suggestions and possible failures.
	Solid Amber	The second state of the LED at switching the device on indicates that the POWER_GOOD signal is active. It also indicates that the power supply is fine.
	Blinking White	The device is in a low-power state, either S1 or S3. This does not indicate a fault condition.
	Solid White	The device is in the S0 state. This is the normal power states of a functioning machine. The BIOS turns the LED to this state to indicate it has started fetching op-codes.

Diagnostic Indicator Table

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 desktops by their flat black and recessed Grill on the front face.

Power LED

Power Button LED	State	Description
	Off	The power is Off. LED is blank.
	Blinking Amber	Initial State of LED at switch-on. See the table below for Blinking Amber pattern diagnostic suggestions and possible failures.
	Solid Amber	The second state of the LED at switching the desktop on indicates that the POWER_GOOD signal is active. It also indicates that the power supply is fine.
	Blinking White	The device is in a low-power state, either S1 or S3. This does not indicate a fault condition.
	Solid White	The device is in the S0 state. This is the normal power states of a functioning machine. The BIOS turns the LED to this state to indicate it has started fetching op-codes.

Diagnostic LEDs (Pre-Post)

State	LED Pattern (1 2 3 4 )	LED Description	Power LED	State Assignment	State Description
Pb0a		Off		System Unplugged	The device is not plugged into AC, PSU is not plugged into system board, or control panel not connected to system board.
Pb0b		Off		ACPI S0; Normal Operation	The device is on with no failures detected. This is a BIOS-controlled state and is also S0e.
Pb0c		Off		ACPI S1	Sitting in windows standby state.
Pb1		Off		ACPI S4 or S5	Hibernate or Soft off. System plugged in, but it is either turned off or in Windows Hibernation State.
Pb2		3 - Solid	-	Reserved	Reserved
Pb3		3,4 - Solid		ACPI S3	Suspend RAM to Windows Standby State.
Pb4		2 - Solid	-	Reserved	Reserved
Pb5		2,4 - Solid	-	Reserved	Reserved
Pb6		2,3 - Solid	-	Reserved	Reserved
Pb7		2,3,4 - Flashing On		ACPI S0, hand off to BIOS control	The device is on. The BIOS is not starting. This is the transition state to POST states.
Pb8		1 - Solid	-	Reserved	Reserved
Pb9		1,4 - Flashing On		Non-System board Regulator Failure	A power failure has been detected on a plug-in component such as VRM, Video Riser, or Memory Riser.
Pb10		1,3 - Flashing On		PSU Failure	PSU may be bad, or PSU cable may be crimped creating a short on a main power rail. (PS_ON asserted, PS_PWRGOOD not asserted)
Pb11		1,3,4 - Flashing On		PSU Cable Failure	All PSU cables may not be properly connected to system board. (PS_ON asserted, missing a main power rail)
Pb12		1,2 - Flashing On		System board Regulator Failure	A power failure has been detected in one of the onboard motherboard regulators. A failed motherboard component or by a plug-in device creating a short on a regulated power rail can cause this. (PS_ON asserted, PS_PWRGOOD asserted, SYS_PWRGOOD de-asserted)
Pb13		1,2,4 - Flashing On		Mismatch	Hardware detected a population incompatibility with a critical component such as CPU, VRM, PSU, or MEMORY RISER.
Pb14		1,2,3 - Solid	-	Reserved	Reserved
Pb15		1,2,3,4 - Solid	-	Reserved	Reserved

Diagnostic LEDs (Post)

State	LED pattern (1 2 3 4 )	LED Description	State Name	State assignment	State description	Suggested Resolution
S0a		Off	OFF	OFF	The power LED is Off. No power is supplied to the device.	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.
S0e		Off	ON	Normal Operation, ACPI S0	The power LED is Solid Green, Blue, or White. The device has successfully booted and is operating.
S1		4	RCM	The device is in Recovery Mode.	BIOS checksum failure was detected, and the device is now in recovery mode.	Reset the BIOS and clear the NVRAM If this occurred after Windows updates, check that your startup was not corrupted.
S2		3	CPU	CPU	The CPU configuration activity is in progress, or a CPU failure was detected.	Disconnect all devices and configure the desktop down to PSU, Motherboard, and CPU If the fault continues contact your technical support If the fault stops, plug disconnected parts back one at a time until the fault recurs. Contact your technical support to take this further.
S3		3,4	MEM	Memory	The configuration activity for the memory subsystem is in progress. Appropriate memory modules were detected, but a memory failure has occurred.	Remove all memory from the device, does the LED code change? If it does not, contact your technical support If it does, add the memory modules back one at a time until the fault recurs, test that module in another slot and contact your technical support
S4		2	PCI	PCI device	PCI device configuration activity is in progress, or PCI device failure was detected.	Remove all devices and all internal PCI devices If the fault continues contact your technical support If the fault stops, add parts back one at a time until the fault recurs and contact your technical support
S5		2,4	VID	Video Card	The configuration activity for the video subsystem is in progress, or the video subsystem is failing.	Ensure that the video cable is connected to the correct port Reseat any add-in graphics cards If the 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
S6		2,3	STO	Storage	The configuration of the storage device is in progress, or the storage subsystem is failing.	Reseat the cables from the hard drives to the motherboard If the fault continues, try substituting a known good hard drive into the device and contact your technical support
S7		2,3,4	USB	USB	The configuration activity for the USB subsystem is in progress, or the USB subsystem is failing.	Remove all devices and any internal CRUs If LEDs change, add parts back one at a time until the fault recurs and contact your technical support If the fault remains the same with parts removed, contact your technical support
S8		1	MEM	Memory	The configuration activity for the memory subsystem is in progress. No memory modules are detected.	Reseat all memory modules If the fault continues, try the memory in different slots and contact your technical support
S9		1,4	MBF	Motherboard	A fatal motherboard failure is detected.	Contact your technical support
S10		1,3	MEM	Memory	The configuration activity for the memory subsystem is in progress. Memory modules have been detected but appear to be incompatible or in an invalid configuration.	Reset the BIOS and clear the NVRAM and any previous errors Remove all memory from the device. This includes any graphics cards. Does the LED code change? If it does not, contact your technical support If it does, add the parts back one at a time until the fault recurs, test that part in another slot and contact your technical support
S11		1,3,4	PRV	Other pre-video activity	This indicates routine activity that preceded the video initialization.	Remove all devices and any internal CRUs If LEDs change, add parts back one at a time until the fault recurs and contact your technical support If the fault remains the same with parts removed, contact your technical support
S12		1,2	CFG	Resource configuration	The desktops resource configuration is in progress.	Reset the BIOS and clear the NVRAM and any previous errors Remove all devices If LEDs change, add parts back one at a time until the fault recurs and contact your technical support If the fault remains the same with parts removed, contact your technical support
S13		1,2,4		Reserved	This is reserved for future use. This pattern is being considered to indicate the Visual Off state on the desktop.	Reserved
S14		1,2,3	POV	Other post-video activity	This indicates routine desktop activity after the video initialization.	Troubleshoot as per the error message on-screen
S15		1,2,3,4	STD	Boot hand off	This indicates the End of the POST process. LEDs are in this state briefly as POST completes. Once the hand-off to the operating system is done, the LEDs turn off and transition to S0e state.	The Power On Self-Test has passed all checks Troubleshoot the hard drive and the Operating System

This series had a combination of Power button LED states with the diagnostic LEDs 1, 2, 3, 4. The diagnostics LEDs are on the front of the chassis.

Power LEDs

Off	Blinking Amber	Solid Amber	Solid Green	Blinking Green

Diagnostics LEDs

Light Pattern		Problem Description	Suggested Resolution
Diagnostic LEDs	Power Button LED
		The device is either turned off or not receiving power.	Reseat the power cable in the power connector on the back of the device and the electrical outlet. Bypass power strips, power extension cables, and other power protection devices to verify that the device turns on properly. Ensure that any power strips being used to 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 device. Allow one minute for the power to drain. Plug the device into a working electrical outlet and press the power button.
	Blinking	A possible system board, power supply, or peripheral failure has occurred.	Power off the device, leaving the desktop plugged in. Press and hold the 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 devices, and press and hold the test button on the power supply. 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.
		There is no CPU present.	Reinstall the CPU and restart the desktop. If the device 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 desktop. If the device starts, 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 device. If available, install verified working memory of the same type into your desktop.
		A possible CPU or system board failure has occurred.	Replace the CPU with a known good CPU. If the desktop still fails to boot, inspect the CPU socket for damage.
		BIOS may be corrupt or missing.	The devices hardware is operating, but the BIOS may be corrupt or missing.
		A possible motherboard failure has occurred.	Remove all peripheral cards from the PCI and PCI-E slots and restart the desktop. If the device boots, add the peripheral cards back one by one until you find the bad one.
		Power connector not installed properly.	Reseat the 2x2 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 device. If the desktop 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 devices, and restart the device. If the desktop boots, add the peripheral cards back one by one until you find the bad one. If the problem persists, the motherboard may be bad.
		A possible coin-cell battery failure has occurred.	Remove the coin-cell battery for one minute, reinstall the battery, and restart.
		The device is in a standard on condition. The diagnostic lights are not lit after the desktop 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 device. If the desktop starts, 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 desktop.
		A possible graphics card failure has occurred.	Reseat any installed graphics cards. If available, install a working graphics card into your desktop.
		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 device. If the desktop starts, 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 desktop.
		Memory modules are detected, but a memory configuration or compatibility error has occurred.	Ensure that no special requirements for memory module or connector placement exist. Ensure that the desktop supports the memory that you are using.
		A possible expansion card failure has occurred.	Determine if a conflict exists by removing an expansion card (not a graphics card) and restarting the device. If the problem persists, reinstall the card you removed, then remove a different card and restart the device. Repeat this process for each expansion card installed. If the device starts, troubleshoot the last card removed from the desktop for resource conflicts.
		A possible motherboard resource or hardware failure has occurred.	Clear CMOS. Disconnect all internal and devices, and restart the device. If the desktop boots, add the peripheral cards back one by one until you find the bad one. If the problem persists, the motherboard or a motherboard component may be 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 confirm that 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 that the boot sequence is correct for the devices installed on your desktop.

Dell Precision desktops have a long history of integrated diagnostic indicators. These can be audible beeps and specific diagnostics LEDs to indicate when during the Power On Self-Test (POST) a device is having issues.

These models had a block of 1, 2, 3, 4, LEDs on the front of the chassis that either lit up Green or were off. A table below is included below with what these indicated. These models were primarily Tower desktops.

Diagnostic LEDs

LED Pattern (1 2 3 4)	LED Pattern	State Name	State Description	Suggested Resolution
	Off	Off	POST completes — 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 that your startup was not corrupted.
	3	CPU	CPU configuration activity or failure; CPU Cache failure	Disconnect all devices and configure the device down to the PSU, Motherboard, and CPU If the fault continues contact your technical support If the fault stops, plug disconnected parts back one at a time until the fault recurs. Contact your technical support to take this further.
	34	MEM	Configuration activity for the memory subsystem or failure	Remove all memory from the device, does the LED code change? If it does not, contact your technical support If it does, add the memory modules back one at a time until the fault recurs, test that module in another slot and contact your technical support
	2	PCI	PCI device configuration or failure	Remove all devices and all internal PCI devices If the fault continues contact your technical support If the fault stops, add parts back one at a time until the fault recurs and contact your technical support
	2 4	VID	Video subsystem configuration or failure	Ensure that the video cable is connected to the correct port Reseat any add-in graphics cards If the 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 hard drives to the motherboard If the fault continues, try substituting a known good hard drive into the desktop and contact your technical support
	234	USB	USB subsystem configuration activity or failure	Remove all devices and any internal CRUs If LEDs change, add parts back one at a time until the fault recurs and contact your technical support If the fault remains the same with parts removed, contact your technical support
	1		No memory detected	Reseat all memory modules If the 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 the device, This includes any graphics cards. Does the LED code change? If it does not, contact your technical support If it does, add the parts back one at a time until the fault recurs, test that part in another slot and contact your technical support
	1 34	PRV	This indicates that device activity preceded the video initialization.	Remove all devices and any internal CRUs If LEDs change, add parts back one at a time until the fault recurs and contact your technical support If the 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 devices If LEDs change, add parts back one at a time until the fault recurs and contact your technical support If the fault remains the same with parts removed, contact your technical support
	12 4		Reserved	Reserved
	123	POV	POST completes — Onscreen error message.	Troubleshoot as per the error message on-screen
	1234	STD	POST completes — operating system hand-off complete.	The Power On Self-Test has passed all checks Troubleshoot the hard drive and the Operating System

Beep Codes

See the table for definitions of the acronyms within this article.