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.

How to obtain this update or hotfix

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.

Method 1: Windows Update

This update is available from Windows Update.

Method 2: Microsoft Download Center

The following files are available for download from the Microsoft Download Center:
Operating systemUpdate
All supported x86-based versions of Windows 8.1Download 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.

Method 3: Hotfix package for Windows 8.1

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:

Note 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.

Update or hotfix detail information


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.

Registry information

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

Restart requirement

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

Update or hotfix replacement information

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


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


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.

Id. de artículo: 3033446 - Última revisión: 21 abr. 2015 - Revisión: 1