First introduced in Windows Vista. It measures the capability of your computer's hardware and software configuration and expresses this measurement as a number called a base score ranging from 1.0 to 7.9.
The score is calculated after the utility performs various tests benchmarking the CPU, Memory, Graphics and Hard- disk etc. Each of the components receive an individual subscore. Your computer's base score is determined by the least of the subscores. For example, if the lowest subscore of an individual hardware component is 4.9, then the base score is 4.9.
To view the Windows Experience Index, Right click on Computer button
in the Start Menu and open Properties from the menu that appears. In this System Properties dialog box you can see your computers base score.
Windows Experience Index may not be available as soon as you install
the OS. To activate:
l Click on the “System rating is not available” link to start the tests in the Performance Information and Tools dialog box.
l Click on the “Rate this computer” button to start the performance evaluation tests. It may take a few minutes depending on your computer’s hardware.
You may use the Re-run the assessment link to recalculate the score at any time. Once you change any of the critical hardware in your computer, you have to be refresh or Re-run the assessment. To view more detailed information about the hardware on your computer, click on ‘View and print details’.