Reference Guide

Dell - Internal Use - Confidential
Internal Use - Confidential
In addition, to clarify memory volatility and data retention in situations where the system is
put in different ACPI power states, the following is provided (ACPI power states are S0, S1,
S3, S4 and S5):
 S0 state is the working state where the dynamic RAM is maintained and is read/written
by the processor.
 S1 state is a low wake-up latency sleeping state. In this state, no system context is lost
(CPU or chip-set) and hardware maintains all system contexts.
 S3 is called “suspend to RAM” state or stand-by mode. In this state, the dynamic RAM is
maintained. Dell systems will be able to go to S3 state if the OS and the peripherals
used in the system support S3 state. Linux and Windows 7 support S3 state.
 S4 is called “suspend to disk” state or “hibernate” mode. There is no power. In this state,
the dynamic RAM is not maintained. If the system has been commanded to enter S4
state, the OS will write the system context to a non-volatile storage file and leave
appropriate context markers. When the system returns to the working state, a restore
file from the non-volatile storage can occur. The restore file has to be valid. Dell
systems will be able to go to S4 state if the OS and the peripherals support S4 state.
Windows 7 support S4 state.
 S5 is the “soft” off state. There is no power. The OS does not save any context to wake
up the system. No data will remain in any component on the system board, i.e. cache
or memory. The system will require a complete boot when awakened. Since S5 is the
shut-off state, coming out of S5 state requires power-on which clears all registers.
The following table shows all the states supported by Precision 5540.
Model Number
S0
S1
S3
S4
S5
Dell Precision 5540
X
X
X
X
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