The RenderCapability.Tier incorrectly reports some display adapters as Tier 0 on some machines with XPDM divice drivers with the RC1 release of Windows Presentation Foundation.  Please see the RC1 release notes for more information.

Since this issue does not prevent the use of hardware acceleration when rendering on either XPDM or WDDM the recommendation is to temporarily ignore the
RenderCapability.Tier API on affected machines.

If testing with the tiering API on RC1 is required this small C# program may work around the issue by deleting HardwareInformation.MemorySize keys which are of type binary and recreating them as DWORDs.

To minimize risk the program will attempt to emit a .reg file to undo any changes made, but modifying the registry is an at your own risk operation and may cause issues with both WPF and non-WPF applications.  In the worst case you may be required to reinstall the operating system.

The tiering issue will be addressed in the next release of the WPF.  Remember to undo any changes you have made to the registry when you upgrade to the next release.

[Courtesy of Daniel Lehenbauer]