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9.13. Energy SaverThe Energy Saver program helps you and your Mac in a number of ways. By blacking out the screen after a period of inactivity, it prolongs the life of your monitor. By putting the Mac to sleep half an hour after you've stopped using it, Energy Saver cuts down on electricity costs and pollution. On a laptop, Energy Saver extends the length of the battery charge by controlling the activity of the hard drive and screen.
Best of all, an old friend is back, to the joy of longtime Mac veterans : the option to have your computer turn off each night automatically, and turn on again at a specified time in anticipation of your arrival at the desk. 9.13.1. Sleep TabThe Energy Saver controls are very different on a laptop Mac and a desktop. On a desktop Mac, you see a pair of sliders; on a laptop, you have to click Show Details to see them (Figure 9-10). In any case, the top slider controls when the Mac will automatically go to sleep ”any-where from one minute after your last activity to Never. (Activity can be mouse movement, keyboard action, or Internet data transfer; Energy Saver won't put your Mac to sleep in the middle of a download.) At that time, the screen goes dark, the hard drive stops spinning, and your processor chip slows to a crawl. Your Mac is now in sleep mode, using only a fraction of its usual electricity consumption. To wake it up when you return to your desk, press any key. Everything you were working on, including open programs and documents, is still onscreen, exactly as it was. (To turn off this automatic sleep feature entirely, drag the slider to Never.) Note: On Macs of old, the beauty of the independent "Put the display to sleep" slider was that you could make the screen go dark before the Mac itself. That way, the Mac would awaken instantly when you touched a key or clicked the mouse.In Mac OS X, the Mac always wakes almost instantly from sleep ”one of the great payoffs of Mac OS X. In other words, there's only one good reason left to set the screen to sleep independently of the Mac itself: so that your Mac will run its standard middle-of-the-night maintenance routines, even while the screen is off to save power. Finally, "Put the hard disk(s) to sleep when possible" saves even more juice ”and noise ”by letting your drives stop spinning when not in use. The downside is a longer pause when you return to work and wake the thing up, because it takes a few seconds for your hard drive to "spin up" again. 9.13.2. Laptop OptionsAs noted above, Energy Saver on a laptop offers quite a few additional controls (see Figure 9-10). That's because power management is ten times more important on a laptop, where every drop of battery power counts. The pop-up menus at the top of the dialog box, for example, let you create different settings for the two states of life for a laptop, when it's plugged in (Power Adapter) and when it's running on battery power (Battery). (This two-state menu, new in Tiger, is much more logical than the setup in previous Mac OS X versions.) Once you've indicated which setting you want to adjust, you can then use the Optimization pop-up menu to choose a canned Energy Saver setting, depending on where you want to fall on the speed-vs.-battery-life spectrum. For example, when you're adjusting the settings for battery-only operation, you can choose Better Battery Life (screen and laptop go to sleep relatively quickly, your processor chip slows down, and the screen brightness dims) or Better Performance (screen sleeps after five minutes, laptop after fifteen, processor runs at top speed). The Custom option just means "none of the above." Whenever you adjust one of the sliders or checkboxes, Energy Saver automatically changes the pop-up menu to say Custom. Mac OS X remembers your settings here. If you choose one of the presets and then choose Custom again, your hand-adjusted settings remain in place. 9.13.3. Scheduled Startup and ShutdownBy clicking the Schedule button, you can set up the Mac to shut itself down and turn itself back on automatically (Figure 9-10, bottom). If you work 9 to 5, for example, set the Mac to turn itself on at 8:45 a.m., and shut itself down at 5:30 p.m. ”an arrangement that conserves electricity, saves money, and reduces pollution, but doesn't inconvenience you in the least. In fact, you may come to forget that you've set up the Mac this way, since you'll never actually see it turned off.
Note: The Mac doesn't shut down automatically if you've left unsaved documents open onscreen. It will go to sleep, though. 9.13.4. Waking and Other OptionsClick the Options tab to summon a few more controls:
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