Datasheet 161
Functional Description
5.13 Power Management
5.13.1 Features
• Support for Advanced Configuration and Power Interface, Version 4.0a (ACPI)
providing power and thermal management
— ACPI 24-Bit Timer SCI and SMI# Generation
• PCI PME# signal for Wake Up from Low-Power states
• System Sleep State Control
— ACPI S3 state – Suspend to RAM (STR)
— ACPI S4 state – Suspend-to-Disk (STD)
— ACPI G2/S5 state – Soft Off (SOFF)
— Power Failure Detection and Recovery
—Deep S4/S5
• Intel Management Engine Power Management Support
— Wake events from the Intel Management Engine (enabled from all S-States
including Catastrophic S5 conditions)
5.13.2 PCH and System Power States
Table 5-24 shows the power states defined for PCH-based platforms. The state names
generally match the corresponding ACPI states.
Table 5-24. General Power States for Systems Using the PCH (Sheet 1 of 2)
State/
Substates
Legacy Name / Description
G0/S0/C0
Full On: Processor operating. Individual devices may be shut down or be placed
into lower power states to save power.
G0/S0/Cx
Cx State: Cx states are processor power states within the S0 system state that
provide for various levels of power savings. The processor initiates C-state entry
and exit while interacting with the PCH. The PCH will base its behavior on the
processor state.
G1/S1
S1: The PCH provides the S1 messages and the S0 messages on a wake event.
It is preferred for systems to use C-states than S1.
G1/S3
Suspend-To-RAM (STR): The system context is maintained in system DRAM,
but power is shut off to non-critical circuits. Memory is retained and refreshes
continue. All external clocks stop except RTC.
G1/S4
Suspend-To-Disk (STD): The context of the system is maintained on the disk.
All power is then shut off to the system except for the logic required to resume.
G1/Deep S4
Suspend-To-Disk (STD): The context of the system is maintained on the disk.
All power is shut off except for minimal logic that allows exiting Deep S4.
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