Reference Guide

To help clarify memory volatility and data retention in situations where the system is put in different ACPI power
states, the following information is provided regarding ACPI power states S0, S1, S3, S4 and S5:
 S0 state is the working state where the dynamic RAM is maintained and is read/write 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 if the OS and the peripherals used in the system
supports S3 state. Win98 SE, Win 2K, Win XP and Windows Vista 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, the OS will write
the system context to a non-volatile storage file and leave appropriate context markers. When the
system is coming back 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 if the OS and the peripherals
support S4 state. Win 2K, Win XP and Windows Vista 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 requires power on which clears all registers.
The Precision workstation T5500 supports all of the above states.
Please direct any questions to the undersigned
Very truly yours;
Dell Marketing L.P.