The DepthBoundsTest11 sample shows how to use the Depth Bounds driver extension.
Depth Bounds Test is a feature on AMD Radeon™ HD 7000 series cards and later. It checks to see if the current depth values are within a certain range (bounds). Drawing is allowed for pixels where the depth is in range, and culled for depths outside the bounds.
Note that the comparison is made with the current depth values in the depth buffer, not the depth value of the pixel to be written. The sample demonstrates a performance improvement you can get with this feature when using deferred rendering.
The depth bounds test functionality is accessed through the AMD GPU Services (AGS) library.
The AMD GPU Services (AGS) library provides software developers with the ability to query AMD GPU software and hardware state information that is not normally available through standard operating systems or graphics APIs.