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Control panel message Description Recommended action
Parity Check 2 Parity RAM failure. Run Computer Setup and Diagnostic utilities.
System will not boot without fan CPU fan not installed or disconnected in
VSFF chassis.
1. Remove the computer cover, press the
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.
Ensure the heatsink is properly seated
and installed.
2. If the fan is plugged in and the heatsink
is properly seated but the fan does not
spin, then replace the heatsink-fan
assembly.
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.
Table C-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.
Table C-1 Numeric Codes and Text Messages (continued)
212 Appendix C POST Error Messages