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Power Management
Power management standard
System power management states
Processor power management states
Chapter 1
Item
ACPI 1.0b/2.0/3.0
Mechanical Off (G3) – All system devices are turned off
completely.
Soft Off (G2/S5) – OS initiated shutdown. All devices
in the system are turned off completely.
Working (G0/S0) – Individual devices such as the
processor and hard disk may be power managed in
this state.
S3 Sleeping State
CPU set power down
VGA suspend
Audio power down
Hard disk power down
Optical drive power down
Card reader function suspend
S4 Sleeping State (hibernation mode) – All system
states and data are saved onto disk before power
shutdown. The same session is restored the next time
the system is powered on.
To further conserve power in a Working state, the
processor enters a low-power state when the OS is idle.
C1 state – CPU halt instruction
C2 state – CPU stop grant state
C3 state – CPU stop clock state
Specification
101
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