CPU throttling no longer works correctly after you resume from Away mode on a computer that is running Update Rollup 2 for Windows XP Media Center Edition 2005 (916197)


The information in this article applies to:

  • Microsoft Windows XP Media Center Edition 2005
Important This article contains information about how to modify the registry. Make sure to back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows registry

SYMPTOMS

Consider the following scenario. You are using a computer that is running Update Rollup 2 for Windows XP Media Center Edition 2005. This computer has a dual-core processor and supports Away mode. However, when the computer resumes from Away mode, the operating system no longer throttles the CPU correctly.

Note The CPU throttling feature limits power consumption and heat generation on a computer that supports this functionality.

RESOLUTION

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk. To resolve this problem, add a NoThrottle DWORD entry that has a value of 1 to the following registry subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ARSVC\Parameters

This registry setting enables the processor driver to throttle the CPU after a computer that has a dual-core processor resumes from Away mode. Specifically, the processor driver tells the operating system not to enable throttling when the computer is using Away mode. The processor driver uses its enhanced speed-stepping functionality to handle transitions into and out of Away mode.

To add this registry entry, follow these steps:
  1. Click Start, click Run, type regedit in the Open box, and then click OK.
  2. Locate and then click the following registry subkey:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ARSVC\Parameters

  3. On the Edit menu, point to New, and then click DWORD Value.
  4. Type NoThrottle for the name of the DWORD value, and then press ENTER.
  5. Right-click NoThrottle, and then click Modify.
  6. In the Value data box, type 1, and then click OK.
  7. Close Registry Editor, and then restart the computer.
Note This registry entry applies only to a computer that has a dual-core processor.

STATUS

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

MORE INFORMATION

Media Center Technical Support

Because Microsoft Windows XP Media Center Edition was included with your hardware device or system, the hardware manufacturer provides technical support and assistance for this software. Your manufacturer may have customized the installation with unique components such as specific device drivers and optional settings to maximize the performance of that manufacturer's hardware. If you require technical help with Windows XP Media Center Edition, contact your manufacturer directly because the manufacturer is best qualified to support the software that the manufacturer has installed on the hardware.

You can also visit the Windows XP Media Center Edition product information Web site at the following Microsoft Web site: http://www.microsoft.com/windowsxp/mediacenter/
Modification Type:MajorLast Reviewed:4/4/2006
Keywords:kbtshoot kbExpertiseInter KB916197 kbAudEndUser
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