NVIDIA Kepler not fully compliant with DirectX 11.1

After a discussion on a German a website, NVIDIA confirmed that the Geforce 600 series does not fully support DirectX 11.1 aka is 100% compatible. Well, it doesn't fully support the API. The GTX 680 supports DirectX 11.1 with hardware API eature level 11.0, including all optional features. 

Now that does include a number of features useful for game developers such as ... 

Reply directly from NVIDIA:

• Partial constant buffer updates
• Logic operations in the Output Merger
• 16bpp rendering
• UAV-only rendering
• Partial clears
• Large constant buffers 

We did not enable four non-gaming features in Hardware in Kepler (for 11_1): 

• Target-Independent Rasterization (2D rendering only)
• 16xMSAA Rasterization (2D rendering only)
• Orthogonal Line Rendering Mode
• UAV in non-pixel-shader stages 

So basically, NVIDIA does support 11.1 features with 11_0 feature level through the DirectX 11.1 API.

"We do not support feature level 11_1. This is a bit confusing, due to Microsoft naming. So we do support 11.1 from a feature level for gaming related features."

The competitions AMD's Radeon HD 7000 "Southern Islands" GPU series is fully compliant with DirectX 11.1 (except the rebranded products from the 6000 family).