A. Pre-Vista Windows versions had options to hibernate, which saved the computer's memory state to disk followed by a shutdown, and standby, which placed the computer into a low power-consumption mode. Vista has the sleep and hybrid sleep modes. In the basic sleep mode, the computer enters a low power-consumption mode, keeping programs and data state in memory; in hybrid sleep mode, the computer enters a low power-consumption mode, keeping programs and data state in memory but also writes the memory content to disk, which means in the event of a power outage the computer's state can be recovered from the disk version of the memory state. Hybrid sleep takes slightly longer to go into low power-mode because the memory content has to be written to disk. On my computer, sleep takes 2 seconds to enter, whereas hybrid sleep takes 16 seconds. The extra 14 seconds is worth it to avoid losing data in the event of a power outage.
The Sleep button on the computer puts the computer into sleep or hybrid sleep mode, depending on the configuration of the computer:
- Start the Power Options Control Panel applet (Start, Control Panel, Power Settings).
- Select the "Change plan settings" option for the current power plan.
- On the settings dialog box, click the "Change advanced power settings."
- Scroll down to the Sleep option, expand "Allow hybrid sleep" (on a laptop additional options for On battery or Plugged in" will be displayed) and click On or Off to allow/disallow hybrid sleep, as the figure shows.
- Click OK and close open dialog boxes.
This setting updates the ACSettingIndex (1 for enabled, 0 for disabled) under the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\User\PowerSchemes\<GUID of scheme> key.