Windows System Assessment Tool

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The Windows System Assessment Tool (WinSAT) is a module of Microsoft Windows Vista, Windows 7, and Windows 8 that is available in the Control Panel under Performance Information and Tools (except in Windows 8.1). It measures various performance characteristics and capabilities of the hardware it is running on and reports them as a Windows Experience Index (WEI) score. The WEI includes five subscores: processor, memory, 2D graphics, 3D graphics, and disk; the basescore is equal to the lowest of the subscores.[1][2] WinSAT reports WEI scores on a scale from 1.0 to 5.9 (for Windows Vista), 7.9 (for Windows 7), or 9.9 (for Windows 8).

The WEI enables users to match their computer hardware performance with the performance requirements of software. For example, the Aero graphical user interface will not automatically be enabled unless the system has a WEI score of 3 or higher.[3][4]

The WEI can also be used to show which part of a system would be expected to provide the greatest increase in performance when upgraded. For example a computer with the lowest subscore being its memory, would benefit more from a RAM upgrade than adding a faster hard drive (or any other component).[2]

Detailed raw performance information, like actual disk bandwidth, can be obtained by invoking winsat from the command line. This also allows only specific tests to be re-run.[5] Obtaining the WEI score from the command line is done invoking winsat formal, which also updates the value stored in %systemroot%\Performance\WinSAT\DataStore.[6] (The XML files stored there can be easily hacked to report fake performance values.[7]) The WEI is also available to applications through an API, so they can configure themselves as a function of hardware performance, taking advantage of its capabilities without becoming unacceptably slow.[8]

The Windows Experience Index score is not displayed in Windows 8.1 although the command line winsat tool still exists and operates correctly.[9]


WinSAT in Windows Vista and Windows 7 performs the following tests:

  • Direct3D 9 Aero Assessment
  • Direct3D 9 Batch Assessment
  • Direct3D 9 Alpha Blend Assessment
  • Direct3D 9 Texture Load Assessment
  • Direct3D 9 ALU Assessment
  • Direct3D 10 Batch Assessment
  • Direct3D 10 Alpha Blend Assessment
  • Direct3D 10 Texture Load Assessment
  • Direct3D 10 ALU Assessment
  • Direct3D 10 Geometry Assessment
  • Direct3D 10 Constant Buffer Assessment
  • Windows Media Decoding Performance
  • Windows Media Encoding Performance
  • CPU Performance
  • Memory Performance
  • Disk Performance (includes devices such as Solid-state drives)

While running, the tests show only a progress bar and a "working" background animation. Aero Glass is deactivated on Windows Vista and Windows 7 during testing so the tool can properly assess the graphics card and CPU.

In addition to tests requested by the user, WinSAT is scheduled[clarification needed] to automatically run every week.[dubious ] The default schedule is 1am on Sundays.[dubious ] In Windows 8 WinSAT runs under the maintenance scheduler. The maintenance scheduler collates various OS tasks into a schedule so the computer is not being randomly interrupted by the individual tasks. The scheduler wakes the computer from sleep, runs all the scheduled tasks and then puts the computer back to sleep. During this weekly task WinSAT runs long enough to detect if there have been any hardware changes. If so the tests are run again. If not WinSAT simply ends as the existing scores must be valid.

WinSAT cannot perform the above tests when a laptop is battery-operated.


  1. ^ "Windows 7 WEI Scores 6.0 through 7.9 Explained". Softpedia. Retrieved 3 June 2011. 
  2. ^ a b "Earning the top Windows Experience Index score". Microsoft. Retrieved 3 June 2011. 
  3. ^ "Full screen previews have got disabled. How do I re-enable them?". Microsoft. Retrieved 3 June 2011. 
  4. ^ "What Is the Windows Experience Index". Microsoft. Retrieved 3 June 2011. 
  5. ^ Winsat Command-Line Utility
  6. ^ How can I run the Windows System Assessment Tool (WinSAT) update directly from a command line?
  7. ^ Stupid Geek Tricks: Hacking the Windows Experience Index
  8. ^ "Windows Experience Index: Overview". Microsoft TechNet. Retrieved 24 September 2011. 
  9. ^ Kowaliski, Cyril (8 July 2013). "Windows 8.1 public preview kills the Windows Performance Index". Retrieved 21 September 2013. 

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