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.
Look for the LED on the system board. If the LED is illuminated, the system still has power. Power
off the computer and remove the power cord before proceeding.
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.
Table A-2
Diagnostic Front Panel LEDs and Audible Codes
Activity
Beeps
Possible Cause
Recommended Action
Green Power LED On.
None
Computer on.
None
Green 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 heatsink/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 heatsink/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.
56
Appendix A POST Error Messages
ENWW
