Wednesday, July 22, 2009

Power Management in Windows XP

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Power Management in Windows XP

As laptops have gotten smaller, thinner, and lighter, they've had to sacrifice the longer-lasting power that comes with large batteries. But at the same time, laptop chipsets and processors have gotten smarter about power management, making the most of these smaller batteries. Windows XP provides several options to manage the power consumed by your laptop—or your desktop.

The Power Options will vary depending on the exact hardware configuration you have. To use Power Options, the Inspiron 5100 battery must be Advanced Configuration and Power Interface (ACPI)-compliant, which dictates that all components are capable of power management. If one or more components are not capable of power management, you might not have ACPI functionality, or you might experience erratic behavior.

Power Options in Windows XP allow you to control the power management features of:

Your display

Your hard drive

Shut Down, Hibernate, and Stand by

Low battery warnings

Additionally, many laptop (as inspiron 1100 battery) manufacturers provide even greater control, giving you more components and devices, and allowing you to shut off or reduce the power consumption of specific pieces of your hardware. We can't begin to cover all the options of the various manufacturers and their power management utilities. In this column, we'll discuss how to use power management in Windows XP.

Managing Your Monitor

Power management of your display screen is something that almost everyone is used to these days. It's a good idea to shut off your display when you're not using it, even when you're running a desktop computer. Although laptop displays don't use as much power, it's still a relatively big power consumer.

Reducing Power Consumption by Your Hard Drive

The two biggest users of power on your laptop are the display and the hard drive. Windows XP lets you tell your hard drive to stop spinning when you're not actively using it, allowing you to save energy and thus battery power.

Putting Your Computer on Standby or Hibernate

There are two basic options for putting your laptop to sleep when you're not actively using it, but don't want to completely shut it down—Standby or Hibernate. Standby is energy conserving, because your entire computer switches to a low-power state. Devices, such as the monitor and hard disks, turn off and your computer uses less power. It's easy to return to work, because Standby leaves applications and files open on your desktop. Standby is perfect when you're going to be taking a break because the cabin attendant just came by with what passes for lunch on airplanes these days, and you want to quickly pick up exactly where you left off. (Note that airlines often request that you completely turn off your computer pa3384u-1brs during take off and landing. In Standby mode, your computer might appear to be turned off but it could automatically restart. So shut down your computer completely when it's not in use on an airplane.) Standby is not appropriate for long term use—on many laptops, overnight is probably pushing it on standby. And it has one important limitation—everything is in memory, not yet saved to the hard drive.

Hibernate mode writes an image of what you're currently working on to a special file on your hard drive, and then shuts your computer almost completely off. It takes a bit longer than Standby, since it needs to write to your hard drive . Hibernate also takes a bit longer to resume, since you must go through essentially the normal boot process, although in Windows XP your computer (satellite a60 battery) wakes faster from Hibernate than in previous versions of Windows. The advantage is that you can leave your laptop in Hibernate mode for days without any ill effect. When you start it back up, you'll see everything exactly as you left it. Hibernate is the perfect mode for shutting down for the night or even the weekend.

If you are using Windows XP Home Edition, or Windows XP Professional with Fast User Switching turned on, the Turn Off Computer menu will present the options to Stand By, Turn Off, or Restart your computer. To put your computer into Hibernate mode, click Start, and then click Turn off computer. Press and hold the Shift key. The label under the first button changes from Stand By to Hibernate. Click Hibernate.

Adjusting Low Battery Warnings

In Power Options for Windows XP, you can set the low laptop battery warnings for your computer. You can choose exactly how much warning you'll receive when the Dell laptop battery gets low and what actions are taken. There are two levels: Low Battery Alarm and Critical Battery Alarm. I find I like to set the Low Battery Alarm level to around 10% of remaining battery, which gives me plenty of time to finish up what I'm doing and shut down in an orderly fashion. And I don't have the Low Battery Alarm actually do anything, other than notify me. The Critical Battery Alarm, however, is set to go off at 3% remaining battery and initiates a forced hibernation. This saves my work and lets me later connect to an external power source and pick up exactly where I left off. The one caution here: Make sure you check Force standby or shutdown even if a program stops responding, as shown in Figure 1 below.

Figure 1.

Configuring Power Settings

Using Power Options in Control Panel, you can adjust any power management option that your computer's unique hardware configuration supports. Because these options may vary widely from computer to computer, the options described may differ from what you see. Power Options automatically detects what is available on your computer and shows you only the options that you can control. To configure your power settings:

Click Start, click Control Panel, click Performance and Maintenance, and then click Power Options.

Or, if you see the little latitude d800 battery indicator on your task bar, right-click it and then click Adjust Power Properties. The Power Options Properties dialog box opens, as shown in Figure 2.

Figure 2.

In the Power Options dialog box, you set options for a power scheme. Windows XP comes with several preconfigured profiles. I've shown the Normal profile for my laptop (Latitude d410 battery) here, but you can easily create custom profiles that fine tune the properties for your particular circumstances. You can create a new power scheme by clicking the time settings you want, clicking Save As, and typing a name. I've got one used for playing music CDs, for example, that shuts off the hard drive and screen almost immediately, but doesn't ever put the system into standby mode.

Enabling Hibernation Mode

Finally, if your machine doesn't have Hibernate enabled, it's easy to enable it. If your computer is set up by the manufacturer to support Hibernate: Open the Power Options Properties dialog box and click the Hibernate tab to open the page shown in Figure 3.

Figure 3.

Just click the Enable Hibernation check box and you're all set. You will, however, need enough free disk space to hold all of your memory in a single file. This means, if your laptop has 512 MB of RAM as mine does, you'll need roughly 512 MB of free disk space on drive C.

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Manufacturer's Utilities

Finally, a word on the various system-specific utilities available. In general, if your laptop manufacturer includes a power management utility, it will offer additional features above and beyond what is included in Windows XP, and may actually disable the Windows XP Power Options dialog box. This makes sense, when you think about it—the computer manufacturer certainly ought to know more about the hardware and what its capabilities are, and most of them provide additional power management tuning abilities. On my laptop (PA2487U PA3107U-1BRS), for example, I can set the screen brightness from full bright to too dim to read, depending on how much power is left in the batteries. So if your laptop comes with a power management utility, you'll generally find it offers additional capabilities. Just make sure, if you have an older laptop that you've upgraded to Windows XP, that the utility is compatible with Windows XP. You may need to download a newer version from the manufacturer's Web site as I did.

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