Power consumption may be more than you expect on a computer that is running Windows XP or Windows Server 2003

You may experience one of the following issues with Windows XP or Windows Server 2003:

• A desktop computer or a server that is running Windows XP or Windows Server 2003 may consume more power than you expect.
• When you unplug the AC power on a portable computer, the battery may drain more quickly than you expect. Then, the operating system may shut down prematurely.

This problem may occur if one of the following conditions is true:

• The portable computer cannot enter the deeper Advanced Configuration and Power Interface (ACPI) processor idle sleep states.
  
  This occurs when the USB 2.0 driver leaves the asynchronous scheduler component running continuously. This prevents the processor from entering the deeper ACPI processor idle sleep states (C-states). C-states save power when the processor is not busy. These states range from C0 to C3 or C4. Typically, an idle portable computer uses the C3 and C4 states to reduce power consumption. If an idle portable computer cannot enter or maintain the C3 or C4 states, the power consumption is increased. This problem is fixed by installing the download that is available in this article.
• The USB host controller cannot turn off.
  
  This typically occurs when devices are removed from a nested USB hub that is attached to the host controller. The host controller does not recognize the device removal. Therefore, the controller is never turned off. This prevents the processor from entering the ACPI processor idle sleep states. This problem is not fixed by installing the download that is available in this article.
• The USB host controller uses the periodic scheduler for USB 2.0 devices.
  
  This typically occurs when devices that rely on the periodic scheduler are attached to the host controller. These may be isochronous (Isoch) devices such as audio devices. Or, they may be interrupt devices such as mouse or keyboard. This problem is not fixed by installing the download that is available in this article.

Note Many factors can affect power consumption other than the kind of USB devices and their configuration. For example, many programs that run on portable computers may have different power consumption requirements. Additionally, the different kinds of batteries that are used can also affect battery power. Therefore, you may not notice any improvement in power consumption after you apply this update.

Windows XP update information

The following file is available for download from the Microsoft download center:

Download the Windows XP (KB918005) package now.

Prerequisites

You must install Windows XP SP2 before you install the update.

For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Restart requirement

After you apply this update, the update forces a restart of the computer.

File information

The English version of this update has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Windows Server 2003 hotfix information

A supported hotfix is now available from Microsoft. However, it is intended to correct only the problem that is described in this article. Apply it only to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Windows Server 2003 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Customer Support Services to obtain the hotfix. For a complete list of Microsoft Customer Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Prerequisites

You must install Windows Server 2003 Service Pack 1 (SP1) or Windows Server 2003 SP2 before you install the hotfix.

Note The x64-based versions of Windows do not require you to install Windows Server 2003 SP1 before you install the hotfix.

For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Restart requirement

After you apply this hotfix, the hotfix forces a restart of the computer.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Windows Server 2003 and Windows XP, x64-based versions

Windows Server 2003, Itanium-based versions

Windows Server 2003, x86-based versions

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

Note If you use Windows Vista, you can visit the following Microsoft Web page for help with power consumption and battery life problems: The x64-based versions of Windows Server 2003 and Windows XP Professional x64 Edition are based on the Windows Server 2003 code tree. Service and support activities for Windows XP Professional x64 Edition use the Windows Server 2003 code tree and do not use the Windows XP client tree. For more information about the x64-based versions of Windows Server 2003 and Windows XP Professional x64 Edition, click the following article number to view the article in the Microsoft Knowledge Base: For more information about the terms that are used to describe software updates, click the following article number to view the article in the Microsoft Knowledge Base: