Using the System Utilities
Power Management
Sleep Mode in Windows 7
- Previous versions of Windows had the following two sleep states:
- Standby, which put the computer in the S3 state
- Hibernate, which put the computer in the S4 state
- Windows 7 uses a combination of the S3 and S4 states called hybrid sleep that saves the contents of memory to disk when entering the S3 state.
- The advantages of hybrid sleep include:
- If power is lost in the S3 state, the computer can recover from the S4 state on reboot. No data is lost when there is a power outage in the S3 state.
- Eliminates the requirement to leave Standby mode to enter hibernation. Windows XP required a laptop in the S3 state to wake up to the S0 state to move down to the S4 state. If
there was a problem entering the S4 state, then the laptop would stay in the S0 state, fully
running, and potentially overheat while in a carrying case. As well, the laptop may run out
of battery life and lose data.
- Other enhancements to power management include the following:
- Resume from S3 state in less than 3 seconds
- Resume from S4 state in less than 10 seconds
- Updated USB hub driver that initializes faster
- Optimized use of processor power management
- Support for additional devices such as graphics cards and wireless network cards
- Support for screen brightness in policies
- Enhanced hard drive management by extending the time a hard drive is off
- Closing a laptop case can trigger sleep mode
- Sleep mode as default shutdown option to speed startup