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Article ID: 314748 - Last Review: January 11, 2015 - Revision: 3.0

This article has been archived. It is offered "as is" and will no longer be updated.


The P3.sys driver may not be initialized properly, and no IST (SpeedStep) transitions may be enabled. The driver may not correctly identify the processor as IST-capable, and may exit the initialization with a status of STATUS_UNSUCCESSFUL. This problem occurs on computers that have a Pentium III-M Tualatin processor and a 440MX chipset, and that use the legacy IST interface.


To resolve this problem, obtain the latest service pack for Windows XP. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
322389  ( ) How to Obtain the Latest Windows XP Service Pack
To resolve this problem, obtain the following update from the Microsoft Windows Update Web site:
Collapse this imageExpand this image
Microsoft processor driver version 5.1.2600.28 (
Release Date: March 31, 2002

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:
119591  ( ) How to Obtain Microsoft Support Files from Online Services
Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file. The English version of this fix should have the following file attributes or later:
   UTC Date      UTC Time   Version       Size     File name
   28-Jan-2002   23:59                     5,257   Cpu.inf
   28-Jan-2002   01:56      5.1.2600.28   37,248   P3.sys


Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Windows XP Service Pack 1.

Applies to
  • Microsoft Windows XP Home Edition
  • Microsoft Windows XP Professional
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