We'll stick to your logic, if nvidia prevents AMD cards from rendering, it's because there's code for that effect since the rest of the architectures don't have a problem, and don't talk to me about "support" as if AMD was going to give NVIDIA something to code for CPU support (it's still the same rivalry you mentioned above), it doesn't make sense. Well, we could polite for hours, the rendering works on AMD cards, that's all there is to remember, the graphics have nothing to do with NVIDIA cards, because AMD cards are long gone unlike their CPUs, ok. But that's where it ends.