Computer Tips From A Computer Guy

Understanding the Windows Experience Index in Windows 7

Posted: 02 Mar 2010 03:48 AM PST

Introduced in Windows Vista and carried through to Windows 7, Microsoft's Windows Experience Index (WEI) is an attempt to rate your computer on various performance criteria. Unfortunately, the WEI has met with some harsh criticisms and doesn't seem to be taken seriously in the world of computer hardware and software.

What is the Windows Experience Index?

The WEI is a general measure of your computer's performance capabilities by taking into account five major components. According to the WEI window in Windows 7, these components are:

Processor: Calculations per second
Memory (RAM): Memory operations per second
Graphics: Desktop performance for Windows Aero
Gaming graphics: 3D business and gaming graphics performance
Primary hard disk: Disk data transfer rate

Using a real-time test, Windows 7 will rate your computer on these subscores and determine your WEI by the lowest score among the components above. The minimum possible score is 1.0 and 7.9 is the current maximum possible score.

The score your computer gets today is the same score it will get forever as long as you don't change any hardware or software in your computer. The maximum score, however, changes to take into account advancing technology such as faster processors, memory, and graphics cards.

Get Your WEI Score

To determine your WEI score, click on Start and then right click on My Computer. Select Properties from the menu and the System Information window opens.

Click on Windows Experience Index under the System section in the middle of the window. This opens the Performance Information and Tools window.

If you haven't run the WEI assessment yet, click on Run the Assessment in the bottom right hand corner of the window. If you have already run the assessment, you subscores and score should be displayed in the window.

If you want to rerun the assessment, click Re-run the Assessment in the bottom right hand corner of the window. When the assessment is complete, your scores will be displayed in the window.

What the WEI Numbers Mean

The WEI numbers don't actually represent measures of any particular metric such as clocks per second, polygons per second, or CAS latencies. They simply represent your computer's score against a theoretical maximum. This maximum is a moving target as computer components become faster. As stated above, 7.9 is the current WEI maximum score.

Notice that your actual WEI score is determined by the lowest subscore. If you computer is like most people's, your lowest score is derived from the data transfer rate of your primary hard drive.

Criticisms of the Windows Experience Index

There are three main criticisms of the WEI that weaken its impact on using it for software ratings and other purposes. In fact, the last criticism is a combination of the first two:

One number determines the WEI. Trying to boil down any metric to one number often results in misinformation about the object being measured. Using one number to determine your computing experience would be like judging a student by his/her grade point average (GPA) alone. There are a lot of factors embedded in that GPA much like there are a lot of factors that contribute to an overall computing experience. One number cannot easily represent all of which your computer is capable.

The lowest subscore determines the WEI. Rating a computer by its slowest subscore would be like calculating a student's GPA by using his/her lowest grade ever received in a course. An average such as the mean or medium would be a better representation of your computer's performance capabilities. A particularly low score on one subscore offers a distorted view.

The hard drive ultimately determines the WEI. Since your WEI is calculated taking the lowest subscore and most people's lowest subscore is the hard drive data transfer metric, a computer's hard drive ultimately determines the measure of the WEI and the performance capabilities of a computer. This hardly seems an accurate measure of computer performance.

In the figure above, you can see that the test computer in this example scored 6.9 on gaming graphics. Not a bad score for an nVidia 8800GT graphics card with 512MB of video memory. However, the computer's SATA-300 7200RPM hard drive forces the WEI to be 5.5, significantly less than all of the other subscores.

Although an attempt to create a simplified rating system, the Windows Experience Index falls short on several fronts by being ultra conservative in its procedure for determining computing experience.

Using one number to represent performance, using the lowest subscore for that number, and ultimately having the hard drive determine computer performance combine to create a largely unappealing and inaccurate method of rating Windows or other software experiences on your computer.