Browsing articles tagged with " power states"
Discoveries
Jan 9, 2009
Justin Marty
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Computer Sleep States [On, Sleep, Standby, Hibernate, Off]

Often when editing device properties or BIOS settings, I get confused with power options listed as power state codes. Some of them are useful, but with the evolution of “power-saving” technology, I think some of the differences between some of the power states aren’t so clear, but seemingly unnecessary. Below you will find a table with the power state codes and a short description written in plain English.

Power state
Code
Details
On / Working
S0
 The computer is powered up. If supported, power conservation is handled
by each device.
Sleep
S1
 CPU is stopped. RAM maintains power. Everything else is off, or in low
power mode.
Sleep
S2
 CPU has no power. RAM maintains power. Everything else is off, or in
low power mode.
Standby
S3
 CPU has no power. RAM maintains power, refreshes slowly. Power supply
reduces power. This level might be referred to as “Save to RAM.” Windows
enters this level when in standby.
Hibernate
S4
 Power to most hardware is shut off. Any files in memory are saved to
the hard disk in a temporary file. If configured, the NIC will remain
on for WOL, or AoL. This level is also known as “Save to disk.”
Off
S5
 Everything is off. No files are saved. If configured, the NIC will maintain
power to listen for WOL (Magic) packets. This is known as a shutdown.