Practicing the Black Art (11/02)
Energy Star and Power States
by Vinny La Bash, vlabash@comcast.net
Member of the Sarasota
Personal Computer Users Group, Inc.
What is Energy Star, and why is it important? Energy Star is a labeling program developed by the Environmental Protection Agency certifying that products built to its specifications are energy efficient. They not only cost less to run, there is no premium attached to their purchase price. You can go to and learn that a suite of ENERGY STAR labeled office equipment will cost you about $97 a year to operate. Compared to $185 for the typical computer, monitor, printer, fax, and copier, this gives you an annual savings of $88. That may not sound like much on an individual basis, but multiply that by the hundreds of millions of pieces of office equipment around the country, and the dollar amount is staggering.
What does that have to do with your computer? Energy Star peripherals and components can be "power managed" not only to reduce your electric bills, but to save wear and tear on the mechanical components of your PC, such as disk drives, and cooling fans.
In many instances, noise levels are significantly reduced.
That 17 inch CRT 85 pound monitor on your desktop that's drawing 150 Watts can be reduced to 12 Watts with proper power management. The electricity your PC uses almost always ends up as additional heat, so lowering your energy requirements can cut your air conditioning costs as an additional benefit. Machines equipped with Windows XP can "hibernate" to where power consumption is reduced to virtually zero when they're idle. You continue operations exactly where you left off when your ready to go back to work.
It's very likely you've heard about "sleep mode", "suspend", "stand-by", and "hibernate" among others. What do they mean, and how do you use them to gain the benefits we've mentioned? These terms vaguely describe various levels of power management on your PC. Various vendors define them differently and sometimes use the same term to mean different things.
Fortunately the industry has some well defined standards, and we'll use these as the basis for any comparisons. There are six separate and distinct power modes, sometimes called "sleep states", in use today ranging from S0 to S5.
The first, S0, is defined as Zero Sleep, which means no power management at all. Operation is at the full power state. You turn your machine on and use it completely oblivious to its power consumption. The last, S5, is where the machine uses no power.
In other words, you have turned it off.
S1 through S4 define increasing levels of energy savings. All of us are familiar with the low power state that can be interrupted by moving a mouse or depressing a button on your keyboard. This is the S1 level that turns off your hard drive and monitor and leaves everything else alone. Most vendors refer to this as "sleep" or "standby".
S2 does everything S1 does while also shutting down your CPU and its cache. This too is called "sleep" or "standby".
S3 goes further by shutting down everything except whatever power is needed to keep the contents of memory active. This level may also be called "sleep", "standby", "suspend", and "instant-on".
You can see that the names are not very helpful, and each of the energy states from S1 to S3 all need some electricity to let the PC know when it's time to revert to full power status. If a power failure should occur when your PC is in any of these states, you will lose whatever happened to be in memory.
S4 defines "hibernation". This is where your system preserves whatever is in memory by writing it to a special file before shutting down. Any other settings necessary to restore the system to where it left off are also dutifully recorded and preserved until the system power is restored. This means you can't wake up the system with a mouse click or by jiggling the keyboard. You need to turn the power switch on.
The big difference is your system doesn't need to go through a complete cold start. It quickly restores itself to the state before shutdown. This is usually faster than a normal reboot, and you don't have to reopen any windows or applications. Everything is ready to continue from where you left off. An added bonus is that "hibernate" is not affected by any power failures as the machine is truly shut-off in this mode.
Let's now examine what Microsoft has done with Windows XP in terms of power management. We will confine our examination to the Home Edition.
1. From the Start menu, select Control Panel.
2. Select Performance and Maintenance.
3. Select Power Options.
You now see the Power Options Properties dialog box presenting you with various power management options. Unless you have changed these values, you see the default options. The Power schemes drop down list offers different combinations of power management, depending on whether your machine is a desktop or a laptop and the kind of work that you do. The table below shows the power management combinations that each of the power schemes uses as its default.
If you cycle through the schemes, notice how the values change to suit how you are working and the kind of equipment you are working with. You may not want the default combinations that Microsoft has chosen for you, but you can devise your own scheme and save it under whatever name that makes sense to you. The defaults are nothing more than starting points.
Choose whatever combination of power management options that suits you, click on the Save As... button, and name the new scheme. Keep in mind that if you change the settings and click Apply or OK without entering a new name, you are changing the default values of whatever scheme is showing in the Power scheme list box.
Clicking on the Advanced tab switches to an additional set of options. Your motherboard manufacturer may include options in addition to the ones shown on this dialog box illustration.
You can put a power management icon on the taskbar. This can be important if you're running a laptop, as you can easily check your battery capacity by moving your mouse over the Taskbar icon. If necessary you can then get to the Power Options Properties dialog box with a single mouse click. If you like, you can have the system prompt for a password when emerging from hibernation.
The Power buttons area lets you specify any of five different actions when you press the on/off button:
* abAsk me what to do
* abStand by
* abHibernate
* abShut down
* abDo nothing
After you've decided on the power savings settings, move to the Hibernate tab. Turn Hibernation on by clicking in the check box. This function requires as much hard disk space as you have memory installed. If you have 512 MB of physical RAM, that's how much hard drive space XP is going to set aside for Hibernation mode. The system doesn't compress the data in memory, so you can't cheat on the disk space required.
The free space available is on the disk drive where XP is installed, usually the C:\ drive. If you don't have at least 10% of your hard drive's capacity available as free space after selecting Hibernation mode, you may run into problems. Calculate carefully.
Hibernation is best used on laptops. There are many reports of desktop systems freezing when emerging from hibernation, so a cold boot may not be eliminated. The symptoms do not appear widespread on laptops. Standby mode uses very little power from the laptop's batteries, but it's still a small and constant power drain. Loss of power could leave the battery in a critical state just when you need it most. Hibernate mode requires nothing from the battery. You can leave your laptop in Hibernate for days at a time with no danger of battery drain.
XP displays a generic UPS tab as part of the Power Options Properties dialog box. Your UPS vendor may provide software that will completely replace this tab. This special software contains diagnostic utilities to test the UPS for faults such as a low or leaking battery.
Summary: There's more to power management than turning your system on and off. Create a power management strategy by analyzing your work habits to determine the optimal times for shutting down various system components during periods of inactivity. Try using the hibernate feature to see how well it works on your system configuration. Give your system a break and install a UPS, especially if you live in a lightning prone area like Florida. The data you save may be your own.
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Copyright 2002. This article is from the November 2002 issue of the Sarasota PC Monitor, the official monthly publication of the Sarasota Personal Computer Users Group, Inc., P.O. Box 15889, Sarasota, FL 34277-1889. Permission to reprint is granted only to other non-profit computer user groups, provided proper credit is given to the author and our publication. We would appreciate receiving a copy of the publication the reprint appears in, please send to above address, Attn: Editor. For further information about our group, email: admin@spcug.org/ Web: http://www.spcug.org/
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