Microsoft KB Archive/912437

= Some system tools may report processor speeds incorrectly on a multiprocessor computer that is running Windows Server 2003 =

Article ID: 912437

Article Last Modified on 10/11/2007

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APPLIES TO


 * Microsoft Windows Server 2003, Standard Edition (32-bit x86)
 * Microsoft Windows Server 2003, Datacenter Edition (32-bit x86)
 * Microsoft Windows Server 2003, Enterprise Edition
 * Microsoft Windows Server 2003, Web Edition
 * Microsoft Windows Server 2003, Datacenter Edition for Itanium-Based Systems
 * Microsoft Windows Server 2003, Enterprise Edition for Itanium-based Systems
 * Microsoft Windows Server 2003, Standard x64 Edition
 * Microsoft Windows Server 2003, Datacenter x64 Edition
 * Microsoft Windows Server 2003, Enterprise x64 Edition

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SYMPTOMS
When you use mixed-speed processors on a multiprocessor computer that is running Microsoft Windows Server 2003, certain system tools may report processor speeds incorrectly.

For example, Device Manager may report a higher speed than the current speed for one of the processors. In this case, Device Manager reports the speed that the processor can run at instead of the speed that the processor is actually running at.

Note When you use mixed-speed processors on a Windows Server 2003-based computer, all processors will run at the speed of the slowest processor.



CAUSE
This problem occurs because certain system tools such as Device Manager use the CPUID instruction to read registry information directly from the processor during startup. This information reflects the speed that the processor can run at, and may not be a reflection of how the processor is actually used.

Note This problem may not affect other system reporting tools such as MSinfo32 or DXDiag. These tools either query each processor individually or test the processor to show the current processor frequency.



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
Certain system tools such as Device Manager read the processor speed information from a registry location that is read during startup. The information is retrieved directly from the processor by using the CPUID instruction.

In a multiprocessor environment, the processor that is used depends which processor is initialized at startup. Most multiprocessor systems use matched processors with identical steppings and speeds. However, if a processor has been replaced or added at a later date, the new processor may be able to run at a higher speed.

Important If a multiprocessor system contains processors that have different capabilities, the system must use the processor that has the lowest feature set as the bootstrap processor. If the system does not use the lowest featured processor as the bootstrap processor, you may experience system instability. Contact the system manufacturer to determine how to configure the system to use the processor that has the lowest feature set as the bootstrap processor. For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base:

888282 Different ways to determine CPU speed in Windows XP or in Windows Server 2003

902247 Availability of hardware-based Data Execution Prevention on multiprocessor systems that are running Windows Server 2003 with Service Pack 1

Note If you are using an Intel Itanium 2 processor-based computer that is running Windows Server 2003, visit the following Microsoft Web site for more information:

http://www.microsoft.com/whdc/system/CEC/SMP.mspx

Technical support for x64-based versions of Microsoft Windows
Your hardware manufacturer provides technical support and assistance for x64-based versions of Windows. Your hardware manufacturer provides support because an x64-based version of Windows was included with your hardware. Your hardware manufacturer might have customized the installation of Windows with unique components. Unique components might include specific device drivers or might include optional settings to maximize the performance of the hardware. Microsoft will provide reasonable-effort assistance if you need technical help with your x64-based version of Windows. However, you might have to contact your manufacturer directly. Your manufacturer is best qualified to support the software that your manufacturer installed on the hardware.

For product information about Microsoft Windows XP Professional x64 Edition, visit the following Microsoft Web site:

http://www.microsoft.com/windowsxp/64bit/default.mspx

For product information about x64-based versions of Microsoft Windows Server 2003, visit the following Microsoft Web site:

http://www.microsoft.com/windowsserver2003/64bit/x64/default.mspx

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

Additional query words: CPU Multiple Winx64 Windowsx64 64bit 64-bit

Keywords: kbtshoot kbexpertiseinter KB912437

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