The Windows Experience Index (WEI) measures the capability of your computer's hardware and software configuration and expresses this measurement as a number that is called a "base score." A higher base score generally means that your computer will run better and faster than a computer that has a lower base score, especially when the computer performs more advanced and resource-intensive tasks. This base score rating will help you more confidently buy additional hardware, programs, and software that are matched to your computer's base score.

The overall WEI is defined as the lowest of the five top-level WEI subscores, where each subscore is computed by using a set of rules and a suite of system assessment tests. The five areas that are scored in Windows 7 are the same areas that were scored in Windows Vista. They are as follows:

Processor
Memory (RAM)
Graphics (general desktop work)
Gaming graphics (typically 3D)
Primary hard disk
Although the scoring areas are the same, the ranges have changed. In Windows Vista, the WEI scores ranged from 1.0 to 5.9. In Windows 7, the range was extended upward to 7.9.

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How to reset WEI or Windows Experience Index

Cannot Update Windows Experience Index.