WinSAT

The Windows System Assessment Tool (WinSAT) is a component included in Windows Vista onwards, and runs various tests on a user's PC, giving a WEI (Windows Experience Index) score which can be used to determine the relative performance of a computer.

Tests
On Windows 7, the suite runs five tests, focusing on the:
 * Processor,
 * Memory (RAM),
 * Graphics,
 * Gaming graphics,
 * Primary hard disk.

Scoring
The lowest of the five criteria mentioned above is reported as the WEI score. The rationale for doing so was based on the idea that upgrading the weakest link in the computer would most likely boost the overall performance of the computer.

The maximum score possible is dependent on the Windows version.
 * For Windows Vista only, the maximum score is 5.9.
 * For Windows 7 only, the maximum score is 7.9.
 * For Windows 8 onwards, the maximum score is 9.9.

D3D effects
It is also possible to display D3D effects on WinSAT. For example, running the command  will display the below effect:

WinSAT 'aurora'
On Windows Vista, the program contains a hidden aurora which can be invoked by typing  at the command line. A 2004 aurora illustration from Robert Stein (who designed graphics and visualizations for Windows) suggests that both WinSAT and WEI were intended for the pre-reset operating system: "A real-time version of this was custom designed for the OOBE (Out Of Box Experience) during the first install. When the installer rates your systems hardware, to determine if it can handle the Glass display, it would use the real-time Aurora to throw data at the systems cpu and gpu while it also lets the user now that “something” is going on, and the system hasn’t stalled."

- Robert Stein

The now-defunct longhorn.ms site also notes that: "No traces of this aurora are present in any pre-reset Longhorn builds. After the reset the system assessment tool, WinSAT, was introduced which quite noticeably uses various DirectX shader files dating from April 2004 which is still before the Longhorn project reset. Build 5219’s WinSAT includes an aurora assessment remarkably similar to Robert Stein’s concepts. If you’d like to have a look at this effect yourself, download the package below which includes WinSAT files from various builds. Note that by the time of build 5308, the fully DirectX rendered aurora was replaced by much less sophisticated moving PNG images with some DirectX light effects."

- Melcher, longhorn.ms