Display, sleep, and hibernate idle timers

Traditional sleep (S3) and Modern Standby systems implement both a display idle time-out and a sleep idle time-out. The reason for providing two separate time-outs is to allow the system to stay turned on and fully running, but save power by turning off the display. If a user sets the two timeouts to be the same on a modern standby PC, the power model is similar to that used by most smartphones: when the screen is off, the system is always in a low-power mode and always connected to the Internet.

Mobile systems also support the ACPI Hibernate (S4) state. Hibernate is used to reduce battery drain during sleep by saving all information in memory to the disk and powering off the system completely. Although Modern Standby systems support Hibernate (S4) state, it is not entered automatically after a fixed amount of time in sleep. Instead, Windows manages Hibernate intelligently, only using it when required to preserve user's battery life. That's because modern standby is a consistently low-power state with long battery life. A modern standby PC is similar to a smartphone-- few users would tolerate their smartphone periodically turning off and entering hibernation. Instead users would expect the system to stay turned on and connected but operate in a low-power mode.

The following table summarizes the differences between a modern standby PC and a traditional sleep PC.

Timer	On a traditional PC	On a modern standby system	Notes
Dim the display	This time-out is no longer supported starting with Windows 8.1. In Windows 10, the display is automatically dimmed 10 seconds before it is turned off.	This time-out is no longer supported starting with Windows 8.1. In Windows 10, the display is automatically dimmed 10 seconds before it is turned off.
Turn off the display	When this time-out occurs, the display immediately turns off. However, the system continues to run and all applications continue to operate normally as if the display was powered on.	When this time-out occurs, the display immediately turns off. However, the system continues to run and all applications continue to operate normally as if the display was powered on.	There is a 5-second grace period between when the display turns off and when the screen off notification is fired.
Put the computer to sleep	When this time-out occurs, the system immediately enters the ACPI Sleep (S3) state. All applications stop execution because all processors will be powered off.	When this time-out occurs, the system enters modern standby and the display is immediately powered down. Then the system steps through the preparation phases described in Prepare software for modern sleep.
Hibernate after	When this timer expires, the system wakes from ACPI Sleep (S3) and immediately enters ACPI Hibernate (S4) to save power.	This time-out is not recommended for modern standby systems.	Modern standby has the intelligence to manage hibernate internally and setting a separate hibernate timeout can result in a loss of some features.