Power Management software enables two ways of reducing power consumption: Device power management and Suspend-Resume.
Device power management automatically reduces the amount of power used by individual devices when they are not in demand to perform some function. Disk drives, monitors, adapters, and even CPUs can provide this power-saving feature. The effect of device power management is transparent to the computer user. The overall system is still in operation, and is able to respond to requests for service from devices. Those devices are able to power up for full service within seconds when needed.
Suspend-Resume is a time-saving feature that allows you to turn off the power to your system without losing the state of your current activities. When you use this feature, your workspace and files are preserved when the system is powered off and restored to the same state when the system is powered on. For example, if you are in the middle of revising a document when you decide to leave, you can power off your system using the Suspend feature and your work session is automatically saved. The next time you power on the system, the Resume feature causes your work to appear in the same state as you left it. Whether a shutdown is initiated automatically (through Power Management software) or manually through keystrokes, the Suspend-Resume feature saves checkpoint information about the state of the system at that time.
Suspend-Resume can be active on your system in the following ways:
Suspend-Resume is used automatically in some Energy Star 2.0-compliant systems.
You can use the keyboard to suspend or resume your system whenever you choose. The steps for doing this are explained in Chapter 4, Using the Suspend-Resume Feature.
Dtpower software can be used to activate Suspend-Resume automatically at designated times.
Do not use System Power Management on systems that do work that should not be interrupted. Conditions where you should choose to not use the Suspend-Resume features are described in Chapter 4, Using the Suspend-Resume Feature.