Processor Power Management in Windows 7 and Windows Server 2008 R2

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Processor Power Management in Windows 7 and Windows Server 2008 R2

October 19, 2012


Windows® 7 and Windows Server® 2008 R2 include updated support for ACPI processor power management (PPM) features, including support for processor performance states and processor idle sleep states on multiprocessor systems. This paper provides details of the support in Windows 7 and Windows Server 2008 R2, describes how PPM functions with the Windows 7 and Windows Server 2008 R2 power policy store, and provides guidelines for firmware developers and system designers.

The information in this white paper applies to the following operating systems:
Windows Server 2008 R2
Windows 7

The current version of this paper is maintained on the Web at:

Processor Power Management in Windows 7 and Windows Server 2008 R2

References and resources discussed here are listed at the end of this paper.

Disclaimer: This document is provided “as-is”. Information and views expressed in this document, including URL and other Internet website references, may change without notice. Some information relates to pre-released product which may be substantially modified before it’s commercially released. Microsoft makes no warranties, express or implied, with respect to the information provided here. You bear the risk of using it.

Some examples depicted herein are provided for illustration only and are fictitious. No real association or connection is intended or should be inferred.

This document does not provide you with any legal rights to any intellectual property in any Microsoft product. You may copy and use this document for your internal, reference purposes.

© 2012 Microsoft. All rights reserved.

Document History



October 19, 2012

Updated GUIDs for Processor Performance Decrease Policy and Processor Performance Increase Policy

January 15, 2010

First publication


Introduction 5

Processor Power Management Changes in Windows 7 5

Windows 7 Processor Power Management Functional Overview 6

Fundamental Components 6

System Firmware (BIOS) 7

Windows Kernel Power Manager 8

Processor Drivers 8

Windows 7 Processor Driver Support 9

The Generic Processor Driver 9

Implementing Processor Power Management for Windows 7 10

Operating System Validation of ACPI Processor Objects 12

Declaring Processors 12

Implementing BIOS Support for Processor Performance States 12

Required Performance State ACPI Objects 12

Optional Performance State ACPI Objects 13

Describing Processor Control Dependencies 13

Implementing BIOS Support for Processor Idle States 14

C‑state Enumeration 14

Implementing BIOS Support for Processor Clock Throttling 16

T‑state Enumeration 16

Core Parking 17

Processor Clocking Control 18

Processor Power Management Validation Tools 19

Windows Resource Monitor 20

Windows Reliability and Performance Monitor 21

Viewing Processor Performance State Usage 21

Viewing Processor Idle State Usage 23

Event Viewer 24

PowerCfg 26

Pwrtest 26

Viewing Supported PPM States 26

Viewing and Logging Processor Idle State Transitions 27

Processor Power Policy on Windows 28

Usage Guidelines 29

Firmware Implementation of Processor Power Policy 29

Windows 7 Power Policy Store 30

Processor Power Policy Settings 31

Processor Performance Policy Settings 31

Processor Core Parking Policy Settings 36

Processor Idle Policy Settings 44

System Cooling Policy Setting 47

Next Steps 47

Resources 48

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Processor Power Management in Windows 7 and Windows Server 2008 R2

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