FIX: The SQL Server database engine and SQL Server Reporting Services may consume more power on Windows client computers than expected

In Microsoft SQL Server 2005 and SQL Server 2008, the database engine and the Reporting Services service may consume more power than expected. This issue may be more apparent on Windows client computers, such as Windows portable computers.

The SQL Server database engine and SQL Server Reporting Services both use a shared component called SQLOS. SQLOS exposes an internal timer. When the internal timer is set to a 1ms granularity, more power consumption than desired may occur on Windows client computers.

Cumulative update information

SQL Server 2008

Important You must install this hotfix if you are running the release version of SQL Server 2008.The fix for this issue was first released in Cumulative Update 6. For more information about how to obtain this cumulative update package for SQL Server 2008, click the following article number to view the article in the Microsoft Knowledge Base:Note Because the builds are cumulative, each new fix release contains all the hotfixes and all the security fixes that were included with the previous SQL Server 2008 fix release. We recommend that you consider applying the most recent fix release that contains this hotfix. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

SQL Server 2008 Service Pack 1

Important You must install this hotfix if you are running SQL Server 2008 Service Pack 1.
The fix for this issue was first released in Cumulative Update 3 for SQL Server 2008 Service Pack 1. For more information about this cumulative update package, click the following article number to view the article in the Microsoft Knowledge Base:Note Because the builds are cumulative, each new fix release contains all the hotfixes and all the security fixes that were included with the previous SQL Server 2008 fix release. Microsoft recommends that you consider applying the most recent fix release that contains this hotfix. For more information, click the following article number to view the article in the Microsoft Knowledge Base: Microsoft SQL Server 2008 hotfixes are created for specific SQL Server service packs. You must apply a SQL Server 2008 Service Pack 1 hotfix to an installation of SQL Server 2008 Service Pack 1. By default, any hotfix that is provided in a SQL Server service pack is included in the next SQL Server service pack.

SQL Server 2005 Service Pack 3

Important You must install this hotfix if you are running SQL Server 2005 Service Pack 3. The fix for this issue was first released in Cumulative Update 5 for SQL Server 2005 Service Pack 3. For more information about this cumulative update package, click the following article number to view the article in the Microsoft Knowledge Base:Note Because the builds are cumulative, each new fix release contains all the hotfixes and all the security fixes that were included with the previous SQL Server 2005 fix release. Microsoft recommends that you consider applying the most recent fix release that contains this hotfix. For more information, click the following article number to view the article in the Microsoft Knowledge Base: Microsoft SQL Server 2005 hotfixes are created for specific SQL Server service packs. You must apply a SQL Server 2005 Service Pack 3 hotfix to an installation of SQL Server 2005 Service Pack 3. By default, any hotfix that is provided in a SQL Server service pack is included in the next SQL Server service pack.

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

After you apply this hotfix, SQLOS will not use the 1ms granularity for the internal timer as the default.

Note The hotfix only fixes this problem for SQL Server Reporting Services and for SQL Server Express editions. For SQL Server Reporting Services users, this change has no effect except to reduce power consumption. For SQL Server Express editions users, this change can reduce power consumption. It can also affect the output of some diagnostic information, such as dynamic management views. For more information about which diagnostics use the 1ms timer provided by SQLOS, visit the following MSDN blog Web site:In this blog post, the 1ms timer is known as the adjusted interrupt timer that uses the timeBeginPeriod API.
For other editions of SQL Server, if you feel that the 1ms timer is causing unwanted power consumption, you can enable trace flag 8038 when the SQL Server service starts.

This will disable the 1ms timer. However, this trace flag will also affect the granularity of some diagnostics, such as dynamic management views.

If you want to use the 1ms timer even after you apply this cumulative update package, or after you upgrade to later builds and releases of SQL Server that contain this change, you can enable trace flag 8049 at startup to force the use of the 1ms timer.

For more information about the Incremental Servicing Model for SQL Server, click the following article number to view the article in the Microsoft Knowledge Base:

For more information about the naming schema for SQL Server updates, click the following article number to view the article in the Microsoft Knowledge Base:

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base: