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Pix is a tool that is distributed for free with Microsoft’s DirectX API. The tool by itself is useful for giving you information about the way you are using the API. However, Pix is an essential tool for a developer who is profiling on an ATI graphics card. ATI offers a plug-in that you can drop into the same directory as PIX that offers a window into the graphics card. This information is invaluable.

The first piece of information you want to use when profiling with pix is a system monitor tool called a “per-frame counter”. This counter returns the percentage of time that the GPU is running idle. Knowing this can help you determine if you are GPU limited or not.