Be sure to check the details
In the previous edition of this book, we expressed some cynicism about the WEI and its value. In Windows 7, we're happy to report, there's considerably more substance beneath these numbers. The WinSAT tests performed by Windows 7 are much more thorough and more granular than those performed by Windows Vista . In fact, we highly recommend that you check the detailed results carefully. Pay special attention to the Notes section at the end, where you might discover that your hard disk is falling short on some workloads . If you see this note, it's an indication that your drive is exhibiting problems related to write caching . Depending on the software you use, you might not notice a performance problem, but for some tasks the difference is noticeable. In that specific case, you might need to replace your hard drive to ratchet performance back up to acceptable levels.
Drivers have a profound influence on WEI scores. If you use a Windows Display Driver Model (WDDM) 1 . 0 graphics driver originally written for Windows Vista, you'll find that the score for graphics tests is capped at 5. 9 . Updating to a Windows 7-compatible WDDM 1 .1 driver will enable WinSAT to run an expanded series of tests and return a score that could be significantly higher
To see the full set of WinSAT test results, use the command-line Windows System Assessment Tool (Winsat. exe). Using Winsat, you can rerun the entire suite (type winsat formal at a command prompt) or retest individual parts of the Windows Experience Index (type winsat -? for the full syntax). You can also save the output as an XML file or redirect the verbal output of the tests to a text file for subsequent review. To see the most recent set of detailed results, type winsat query from a Command Prompt window.
Windows 7 keeps a history of WinSAT performance results that you can use for comparisons. You'll find them in %SystemRoot%\Performance\WinSAT\DataStore, each one stamped with the exact date and time it was run . Minor variations in results between Winsat runs are normal, usually as a result of other processes and services interfering with resource usage. Keeping even an informal record of detailed results over time can help you determine whether a significant change in test scores is normal or a sign of a problem to be found and fixed.
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