Desktop basics
With the various kinds of desktop computers, and the different tasks we use them for, it's hard to pin down an average power consumption target. Our primary source for acceptable desktop power usage is Energy Star, a certification program established by the Environmental Protection Agency that provides consumer electronics and computer manufacturers with a seal of approval indicating a product's power efficiency.
Looking for an Energy Star certification on a product is a great way to determine its green-friendly pedigree, but if you're smart about how you use your desktop, you can reduce your PC's power consumption even more. In addition to saving power, smart desktop power management can also save you money on your utility bill throughout the course of a year. We'll explore the various software and hardware considerations over the next few pages. Before we dive in, we'll present a brief overview of some common terms.
Sleep: Used by Apple's Mac OS X, Windows Vista, and to refer to a low-power state from which your monitor or your PC can quickly return to full power operation. The displays goes dark and the PC cuts power from every component except for system memory. By leaving the memory on, your PC can store information about its last usage state and wake up quickly. Power loss to the system while in sleep mode, such as during a blackout, will lose any unsaved data, including your last usage state.
Standby: The Windows XP version of Sleep.
Suspend: The Linux version of Sleep.
Hibernation: A low-power mode available in Windows Vista and Windows XP that stores necessary recovery information on your PC's hard drive. The computer then powers down completely. It takes longer to recover from hibernate mode than Sleep or Standby, but with the recovery information stored on your hard drive, you can come out of hibernation in the same state as you left it, without having to launch the same programs. You also don't have to worry about data loss in the event of a power outage.
Hybrid sleep: A combination of sleep and hibernate available on some Windows Vista desktops. It saves the data necessary to recover quickly to your hard drive, thus preventing data loss, but it doesn't shut down the computer completely, letting you resume working more quickly than from true hibernation.
Safe Sleep: An Apple term describing a low-power state similar to hybrid sleep. Safe Sleep kicks in automatically when you put a Mac from 2005 or later in Sleep mode. It stores the necessary recovery data on your hard drive to prevent data loss, but it also keeps the data in memory to enable you to wake your Mac up quickly.
