Appendix B: Power / Sleep / Global States Explained - HP Z200 - Small Form Factor Workstation Setup And Configuration Manual

Appendix B: Power / Sleep / Global States
Explained
Under Advanced Configuration and Power Interface (ACPI) specification a PC can
be in one of several Power states. These power states are also known as Sleep (Sx)
states or Global (Gx) states.
S0 is the ON state. The PC is fully functioning. All system devices and
operating system, if available, are running. S0 is also known as G0.
S3 is the Standby (Microsoft terminology) or Suspend-to-RAM state. The
memory subsystem and Vaux power rail remains powered, while the rest of
the system including the processor are not powered. When the system
resumes from S3, the system context remains intact because the system
memory was preserved and powered at all times.
S4 is the Hibernate (Microsoft terminology) or Suspend-to-Disk state. The
system context (memory) is saved to the hard drive as a hibernation file.
When the system resumes from S4, the system context is restored from the
hibernation file. Vaux remains powered, but all other subsystems including
system memory and the processor are not powered.
S5 is the Soft Off state. It is identical to S4 with the exception that the system
context is not saved. When the system resumes from S5, it will power up
and going through POST. S5 is also known as G2.
G3 is the Mechanical Off state. All subsystems are not powered in this state.
The easiest way to achieve this state is by removing A/C power from the
system via unplugging the power cord.
The ME has its own power states (Mx) similar to the Sx states.
M0 is the ON state for the ME when the system is in S0 state. The ME is fully
powered and running.
M3 is the ON state for the ME when the system is in a non-S0 state. The ME is
fully powered and running.
Moff is the OFF state for the ME. The system is in a non-S0 state.
The ME can be set to stay powered and active in all Sx states. If the system (host) is
in S0, then the ME will be in the corresponding M0 state. However, if the system is
in S3, S4, or S5, then the ME will still remain active, but it will be in M3 state.
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