Control panel message
Description
Recommended action
4.
Replace keyboard.
Parity Check 2
Parity RAM failure.
Run Computer Setup and Diagnostic utilities.
Interpreting POST diagnostic front panel LEDs and audible codes
This section covers the front panel LED codes as well as the audible codes that may occur before or during
POST that do not necessarily have an error code or text message associated with them.
WARNING!
When the computer is plugged into an AC power source, voltage is always applied to the system
board. To reduce the risk of personal injury from electrical shock and/or hot surfaces, be sure to disconnect
the power cord from the wall outlet and allow the internal system components to cool before touching.
NOTE:
If you see flashing LEDs on a PS/2 keyboard, look for flashing LEDs on the front panel of the
computer and refer to the following table to determine the front panel LED codes.
Recommended actions in the following table are listed in the order in which they should be performed.
Not all diagnostic lights and audible codes are available on all models.
Activity
Beeps
Possible cause
Recommended action
White Power LED On.
None
Computer on.
None
White Power LED flashes every
two seconds.
None
Computer in Suspend to
RAM mode (some models
only) or normal Suspend
mode.
None required. Press any key or move the mouse to
wake the computer.
Red Power LED flashes two
times, once every second,
followed by a two second pause.
Beeps stop after fifth iteration
but LEDs continue until problem
is solved.
2
Processor thermal
protection activated:
A fan may be blocked or not
turning.
OR
The heat sink/fan assembly
is not properly attached to
the processor.
1.
Ensure that the computer air vents are not
blocked and the processor cooling fan is
running.
2.
Open hood, press power button, and see if the
processor fan spins. If the processor fan is not
spinning, make sure the fan's cable is plugged
onto the system board header.
3.
If fan is plugged in, but is not spinning, then
replace heat sink/fan assembly.
4.
Contact an authorized reseller or service
provider.
Red Power LED flashes three
times, once every second,
followed by a two second pause.
Beeps stop after fifth iteration
but LEDs continue until problem
is solved.
3
Processor not installed (not
an indicator of bad
processor).
1.
Check to see that the processor is present.
2.
Reseat the processor.
Red Power LED flashes four
times, once every second,
followed by a two second pause.
Beeps stop after fifth iteration
but LEDs continue until problem
is solved.
4
Power failure (power supply
is overloaded).
1.
Open the hood and ensure the 4 or 6-wire
power supply cable is seated into the
connector on the system board.
2.
Check if a device is causing the problem by
removing ALL attached devices (such as hard,
diskette, or optical drives, and expansion
cards). Power on the system. If the system
enters the POST, then power off and replace
one device at a time and repeat this procedure
Interpreting POST diagnostic front panel LEDs and audible codes 123
