Product Description 
29 
1.15.1.1  System States and Power States 
Under ACPI, the operating system directs all system and device power state 
transitions.  The operating system puts devices in and out of low-power states based 
on user preferences and knowledge of how devices are being used by applications.  
Devices that are not being used can be turned off.  The operating system uses 
information from applications and user settings to put the system as a whole into a 
low-power state. 
Table 8 lists the power states supported by the board along with the associated 
system power targets.  See the ACPI specification for a complete description of the 
various system and power states. 
Table 8.  Power States and Targeted System Power 
 
Global States 
 
Sleeping States 
Processor 
States 
 
Device States 
Targeted System  
Power 
(Note 1)
 
G0 – working 
state 
S0 – working  C0 – working  D0 – working 
state. 
Full power > 30 W 
G1 – sleeping 
state 
S3 – Suspend to 
RAM.  Context 
saved to RAM. 
No power  D3 – no power 
except for 
wake-up logic. 
Power < 5 W  
(Note 2)
 
G1 – sleeping 
state 
S4 – Suspend to 
disk.  Context 
saved to disk. 
No power  D3 – no power 
except for 
wake-up logic. 
Power < 5 W  
(Note 2)
 
G2/S5  S5 – Soft off.  
Context not saved.  
Cold boot is 
required. 
No power  D3 – no power 
except for 
wake-up logic. 
Power < 5 W  
(Note 2)
 
G3 – 
mechanical off 
AC power is 
disconnected 
from the 
computer. 
No power to the 
system. 
No power  D3 – no power for 
wake-up logic, 
except when 
provided by 
battery or 
external source. 
No power to the system.  
Service can be performed 
safely. 
Notes: 
1.  Total system power is dependent on the system configuration, including add-in boards and peripherals 
powered by the system chassis’ power supply. 
2.  Dependent on the standby power consumption of wake-up devices used in the system.