16.1.3 S3 Sleeping State The S3 state is defined as a low wake-latency sleep state. From the software viewpoint, this state is functionally the same as the S2 state. The operational difference is that some Power Resources that may have been left ON in the S2 state may not be available to the S3 state. As such, some devices may be in a lower power state when the system is in S3 state than when the system is in the S2 state. Similarly, some device wake events can function in S2 but not S3
and:
16.1.4 S4 Sleeping State The S4 sleeping state is the lowest-power, longest wake-latency sleeping state supported by ACPI. In order to reduce power to a minimum, it is assumed that the hardware platform has powered off all devices.
Re: How is this anything new?
16.1.3 S3 Sleeping State
The S3 state is defined as a low wake-latency sleep state. From the software viewpoint, this state is
functionally the same as the S2 state. The operational difference is that some Power Resources that
may have been left ON in the S2 state may not be available to the S3 state. As such, some devices
may be in a lower power state when the system is in S3 state than when the system is in the S2 state.
Similarly, some device wake events can function in S2 but not S3
and:
16.1.4 S4 Sleeping State
The S4 sleeping state is the lowest-power, longest wake-latency sleeping state supported by ACPI.
In order to reduce power to a minimum, it is assumed that the hardware platform has powered off all
devices.