Power must be switched from the normal 1.8 V rail to standby 1.8 V, because the ATX 12v 450 W power supply does not directly supply a standby 1.8 V rail. The sequence to enter Suspend to RAM is as follows:
1.The OS and BIOS prepare for S3 sleep state.
2.The OS sets the appropriate sleep bits in the I/O controller.
3.The I/O controller drives STPCLK to the processors.
4.The processors respond with a
5.The I/O controller indicates an S3 (STR) sleep mode to the MCH via Hub Interface A.
6.The MCH puts DDR memory into the
7.The MCH drives DDR CMDCLK differential pairs and all DDR outputs low.
8.The MCH drives a completion message via Hub Interface A to the I/O controller.
9.The I/O controller turns off all voltage rails (except Standby 5V) from the main power supply by asserting the SLP_S3_N signal.
When in the S3 state, only the standby 5 V rail is available from the power supply. The board uses this standby source to generate 1.8 V standby rail to power the DIMMs.
The asserted SLP_S3_N signal also controls the logic to switch the DIMM power source from main 1.8 V to standby 1.8 V.
4.2.5S4 State
This state is not supported.
4.2.6S5 State
This state is the normal off state whether entered through the power button or soft off. All power is shut off except for the logic required to restart. The system remains in the S5 state only while the power supply is plugged into the electrical outlet. If the power supply is unplugged, this is considered a mechanical off or G3.
4.2.7Wake-Up Events
The types of
4.2.8Wake from S1 Sleep State
During S1 the system is fully powered, permitting support for PCI Express Wake and Wake on PCI PME#.
4.2.9Wake from S3 State
Keyboard press or mouse movement is used to wake from S3.
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User’s Manual | April 2007 |
38 | Order Number: |
