Microsoft KB Archive/940566

= An update is available to support Deep Power Down technology on a Windows XP SP2-based computer that has an Intel Penryn processor =

Article ID: 940566

Article Last Modified on 9/27/2007

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APPLIES TO


 * Microsoft Windows XP Home Edition
 * Microsoft Windows XP Professional

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SYMPTOMS
Consider the following scenario:
 * You are running a Windows XP Service Pack 2 (SP2)-based computer that has an Intel Penryn processor.

Note The Intel Penryn processor has a new power-management state that significantly reduces the power that is used by the processor during idle periods.
 * You let the computer become idle.

In this scenario, the processor cannot efficiently enter the new power-management state as expected.



CAUSE
The mobile Penryn processor has advanced power-management functionality that is known as Deep Power Down technology. Because Deep Power Down technology significantly reduces the power that is used by the processor during idle periods, a portable computer's battery life is extended significantly. However, on a Windows XP SP2-based computer that has a Penryn processor, the system does not efficiently enable this new power-management functionality during idle periods.



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

To resolve this problem, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Web site:

http://go.microsoft.com/?linkid=6294451

Note If additional issues occur or any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. To create a separate service request, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Prerequisites
To apply this hotfix, you must have Windows XP Service Pack 2 installed. For more information about how to obtain the latest Windows XP service pack, click the following article number to view the article in the Microsoft Knowledge Base:

322389 How to obtain the latest Windows XP service pack

Restart requirement
You must restart the computer after you apply this hotfix.

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.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
The Advanced Configuration and Power Interface (ACPI) specification describes processor idle power states as ACPI C-states. When the computer is in an idle state, Windows XP SP2 fully supports ACPI C-states by directing the processor to a low power idle state. Deep Power Down technology represents a recent advancement in processor idle states. This technology may also be recognized by the platform as the ACPI C6 processor power state. This new processor power state must be specifically enabled to work efficiently in Windows XP SP2. This hotfix implements that functionality.

For the more information about Intel Penryn processor, visit the following Intel Web site:

http://www.intel.com/technology/magazine/45nm/coremicroarchitecture-0507.htm?iid=search

Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.

Keywords: kbexpertiseinter kbpubtypekc kbqfe kbhotfixserver KB940566

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