Location and purpose of the power button LED and the diagnostic LEDs

1. Power button LED states

Power LED state	Description
Off	Power is off, LED is blank.
Blinking amber	Initial state of LED at power up. Indicates system has power, but the POWER_GOOD signal is not yet active. If the Hard Drive LED is off, it is probable that the power supply needs to be replaced. If the Hard Drive LED is on, it is probable that an onboard regulator or VRM has failed. Look at the diagnostic LEDs for further information.
Solid amber	Second state of the LED at power up. Indicates the POWER_GOOD signal is active and it is probable that the power supply is fine. Look at the diagnostic LEDs for further information.
Blinking white	System is in a low power state, either S1 or S3. Look at the diagnostic LEDs to determine which state the system is in.
Solid white	System is in S0 state, the normal power state of a functioning machine. The BIOS will turn the LED to this state to indicate it has started fetching operation codes.

2.	Pre-POST (Power On Self Test) diagnostic LED patterns

	Note:
	Depending on the system, the normal power-on state may be either a solid white, green, or blue power LED.

LED pattern (1 2 3 4)	LED description	Power LED	State description
	1- Off 2- Off 3- Off 4- Off		System is not plugged into AC, PSU is not plugged into system board, or control panel not connected to system board.
	1- Off 2- Off 3- Off 4- Off		System is on with no failures detected. This is actually a BIOS controlled state and is also S0e.
	1- Off 2- Off 3- Off 4- Off		Windows Standby State.
	1- Off 2- Off 3- Off 4- Off		Hibernate or Soft off. System plugged in, but either turned off or in Windows Hibernation State.
	1- Off 2- Off 3-Solid 4- Off	-	Reserved
	1- Off 2- Off 3- Solid 4- Solid		Suspend to RAM Windows Standby State.
	1- Off 2- Solid 3- Off 4- Off	-	Reserved
	1- Off 2- Solid 3- Off 4- Solid	-	Reserved
	1- Off 2- Solid 3- Solid 4- Off	-	Reserved
	1- Off 2- Blink 3- Blink 4- Blink		System on. BIOS not execution. This is the transition state to POST states.
	1- Solid 2- Off 3- Off 4- Off	-	Reserved
	1- Blink 2- Off 3- Off 4- Blink		A power failure has been detected on a plug-in component such as VRM, Video Riser, or Memory Riser.
	1- Blink 2- Off 3- Blink 4- Off		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)
	1- Blink 2- Off 3- Blink 4- Blink		All PSU cables may not be properly connected to system board. (PS_ON asserted, missing a main power rail)
	1- Blink 2- Blink 3- Off 4- Off		A power failure has been detected in one of the onboard system board regulators. This could be caused by a failed system board component or by a plug-in device creating a short on a regulated power rail. (PS_ON asserted, PS_PWRGOOD asserted, SYS_PWRGOOD de-asserted)
	1- Blink 2- Blink 3- Off 4- Blink		Hardware detected a population incompatibility with a critical system component such as CPU, VRM, PSU, or MEMORY RISER.
	1- Solid 2- Solid 3- Solid 4- Off	-	Reserved
	1- Solid 2- Solid 3- Solid 4- Solid	-	Reserved

3.	POST diagnostic LED patterns

	Note:
	Unless otherwise notes, the power LED will show as solid white/blue/green (depending on the system) to denote a normal power state.

LED pattern (1 2 3 4)	LED description	State description
	1- Off 2- Off 3- Off 4- Off	Power LED Off. No power is supplied to the system.
	1- Off 2- Off 3- Off 4- Off	Power LED Solid Green/Blue or White. System has successfully booted and is operating normally.
	1- Off 2- Off 3- Off 4- Solid	BIOS checksum failure was detected and the system is now in recovery mode.
	1- Off 2- Off 3-Solid 4- Off	CPU configuration activity is in progress or a CPU failure was detected.
	1- Off 2- Off 3- Solid 4- Solid	Memory subsystem configuration activity is in progress. Appropriate memory modules were detected but a memory failure has occurred.
	1- Off 2- Solid 3- Off 4- Off	PCI device configuration activity is in progress or PCI device failure was detected.
	1- Off 2- Solid 3- Off 4- Solid	Video subsystem configuration activity in progress or video subsystem failure.
	1- Off 2- Solid 3- Solid 4- Off	Storage device configuration in progress or storage subsystem failure.
	1- Off 2- Solid 3- Solid 4- Solid	USB subsystem configuration activity in progress or USB subsystem failure.
	1- Solid 2- Off 3- Off 4- Off	Memory subsystem configuration activity is in progress. No memory modules were detected.
	1- Solid 2- Off 3- Off 4- Solid	Fatal system board failure detected.
	1- Solid 2- Off 3- Solid 4- Off	Memory subsystem configuration activity is in progress. Memory modules have been detected but appear to be incompatible or in an invalid configuration.
	1- Solid 2- Off 3- Solid 4- Solid	Indicates routine system activity preceding video initialization.
	1- Solid 2- Solid 3- Off 4- Off	System resource configuration in progress.
	1- Solid 2- Solid 3- Off 4- Solid	Reserved for future use.
	1- Solid 2- Solid 3- Solid 4- Off	Indicates routine system activity subsequent to video initialization.
	1- Solid 2- Solid 3- Solid 4- Solid	Indicates End of POST process. LEDs are normally in this state briefly as POST completes. Once the hand-off to the OS is done, the LEDs turn off and transition to a fully off state.