Wi-Fi connectivity issues or poor performance on CHT platform computers in Windows 8.1

This article describes an issue that occurs on an Intel Cherry Trail (CHT)-based computer that is running Windows 8.1. You can resolve this issue by using the update or hotfix in this article. Before you install this update or hotfix, check out the Prerequisites section.

This issue occurs because the CHT platform has the following hardware limitations:

  • Touch the CMD and DAT inhibit bits during the tuning procedure causes the tuning to fail.

  • The Preset Value Enable bit does not work with some Wi-Fi modules.

To resolve this issue, we have released an update through Windows Update and Microsoft Download Center. We also have released a hotfix for Windows 8.1. The update or hotfix prevents the Sdbus.sys file from using the Preset Value Enable bit or touching the CMD and DAT inhibit bits during the tuning in the CHT platform.

Important Do not install a language pack after you install this update or hotfix. If you do, the language-specific changes in the update or hotfix will not be applied, and you will have to reinstall the update or hotfix. For more information, see Add language packs to Windows.

This update is available from Windows Update.

The following files are available for download from the Microsoft Download Center:

Operating system

Update

All supported x86-based versions of Windows 8.1

Download Download the package now.

All supported x64-based versions of Windows 8.1

Download Download the package now.

For more 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 prevent any unauthorized changes to the file.

A supported hotfix is 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.

If the hotfix is available for download, there is a "Hotfix Download Available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if 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. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft website:

http://support.microsoft.com/contactus/?ws=supportNote The "Hotfix Download Available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

To apply this update or hotfix, you must have April 2014 update rollup for Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2 (2919355) installed in Windows 8.1.

To apply this update or hotfix, you do not have to make any changes to the registry.

You may have to restart the computer after you apply this update or hotfix.

This update or hotfix does not replace a previously released update or hotfix.

The global version of this update or hotfix installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.

Windows 8.1 file information and notes

  • The files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:

    Version

    Product

    Milestone

    Service branch

    6.3.960 0.17xxx

    Windows 8.1

    RTM

    GDR

  • The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are

    listed separately in the "Additional file information" section. MUM, MANIFEST, and the associated security catalog (.cat) files, are very important to maintain the state of the updated components. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.

For all supported x86-based versions of Windows 8.1

File name

File version

File size

Date

Time

Platform

Intelpep.sys

6.3.9600.17254

36,160

17-Oct-2014

03:15

x86

Pdc-mw.ptxml

Not applicable

4,498

21-Aug-2013

23:40

Not applicable

Pdc.sys

6.3.9600.17254

76,096

17-Oct-2014

03:01

x86

Dumpsd.sys

6.3.9600.17255

131,392

17-Oct-2014

03:15

x86

Sdbus.sys

6.3.9600.17255

199,488

17-Oct-2014

03:15

x86

For all supported x64-based versions of Windows 8.1

File name

File version

File size

Date

Time

Platform

Intelpep.sys

6.3.9600.17254

39,744

17-Oct-2014

04:56

x64

Pdc-mw.ptxml

Not applicable

4,498

22-Aug-2013

06:45

Not applicable

Pdc.sys

6.3.9600.17254

86,336

17-Oct-2014

03:35

x64

Dumpsd.sys

6.3.9600.17255

153,920

17-Oct-2014

04:56

x64

Sdbus.sys

6.3.9600.17255

238,912

17-Oct-2014

04:56

x64

Additional file information

Additional file information for Windows 8.1

Additional files for all supported x86-based versions of Windows 8.1

File property

Value

File name

X86_454b6ff55bb0fb987150c0f560e26f04_31bf3856ad364e35_6.3.9600.17668_none_5b91eb6a597cc9fd.manifest

File version

Not applicable

File size

691

Date (UTC)

28-Jan-2015

Time (UTC)

19:32

Platform

Not applicable

File name

X86_intelpep.inf_31bf3856ad364e35_6.3.9600.17668_none_595e0b1a449dc09c.manifest

File version

Not applicable

File size

2,113

Date (UTC)

28-Jan-2015

Time (UTC)

19:36

Platform

Not applicable

File name

X86_microsoft-windows-pdc_31bf3856ad364e35_6.3.9600.17668_none_3bec446f77b9f9ff.manifest

File version

Not applicable

File size

88,631

Date (UTC)

28-Jan-2015

Time (UTC)

19:36

Platform

Not applicable

File name

X86_sdbus.inf_31bf3856ad364e35_6.3.9600.17668_none_069c1134e5dce5a8.manifest

File version

Not applicable

File size

2,728

Date (UTC)

28-Jan-2015

Time (UTC)

19:36

Platform

Not applicable

Additional files for all supported x64-based versions of Windows 8.1

File property

Value

File name

Amd64_0f483870cafebd5217ebe83ef672115f_31bf3856ad364e35_6.3.9600.17668_none_9f8a658b763340f5.manifest

File version

Not applicable

File size

695

Date (UTC)

28-Jan-2015

Time (UTC)

19:32

Platform

Not applicable

File name

Amd64_intelpep.inf_31bf3856ad364e35_6.3.9600.17668_none_b57ca69dfcfb31d2.manifest

File version

Not applicable

File size

2,117

Date (UTC)

28-Jan-2015

Time (UTC)

19:40

Platform

Not applicable

File name

Amd64_microsoft-windows-pdc_31bf3856ad364e35_6.3.9600.17668_none_980adff330176b35.manifest

File version

Not applicable

File size

88,635

Date (UTC)

28-Jan-2015

Time (UTC)

19:40

Platform

Not applicable

File name

Amd64_sdbus.inf_31bf3856ad364e35_6.3.9600.17668_none_62baacb89e3a56de.manifest

File version

Not applicable

File size

2,732

Date (UTC)

28-Jan-2015

Time (UTC)

19:40

Platform

Not applicable

Status

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

References

See the terminology that Microsoft uses to describe software updates.

Third-party information disclaimer

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.

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