Table 3. Power LED summary
Amber LED state White LED state System state Notes
O O S4, S5
• Hibernate or Suspend to Disk 
(S4)
• Power is o (S5)
O Blinking S1, S3
System is in a low power state, 
either S1 or S3. This does not 
indicate a fault condition.
Previous State Previous State S3, no PWRGD_PS This entry provides for the 
possibility of a delay from 
SLP_S3# active to PWRGD_PS 
inactive.
Blinking O S0, no PWRGD_PS
Boot Failure - The computer is 
receiving electrical power, and 
power supplied by the power 
supply is normal. A device might 
be malfunctioning or incorrectly 
installed. Refer to the table 
below for Amber Blinking Pattern 
diagnostics suggestion and 
possible failures.
Steady O S0, no PWRGD_PS, Code fetch 
= 0
Boot Failure - This is a system 
fault error condition, including 
the power supply. Only the 
+5VSB rail on the power supply 
is working correctly.
O Steady S0, no PWRGD_PS, Code fetch 
= 1
This indicates that the host BIOS 
has started to execute and the 
LED register is now writable.
Table 4. Amber LED blinking failures
Amber LED state White LED state System state Notes
2 1 Bad MBD Bad MBD - Rows A, G, H, and J 
from table 12.4 of SIO Spec - 
Pre-Post indicators [40]
2 2 Bad MB, PSU or cabling Bad MBD, PSU or PSU cabling - 
Rows B, C and D of table 12.4 
SIO spec [40]
2 3 Bad MBD, DIMMS, or CPU Bad MBD, DIMMS or CPU - 
Rows F and K from table 12.4 of 
SIO spec [40]
2 4 Bad coin cell Bad coin cell - Row M of table 
12.4 in SIO spec [40]
Troubleshooting 71