Let's say that I run the same game in two different computers with different GPUs. If for example they are both certified for DirectX 10. Is there a guarantee that the output for a given program (game) is going to be the same regardless the manufacturer or model of the GPU? I am assuming the configurable settings are exactly the same in both cases.
I heard that it is not the case for DirectX 9 and older, but that it is true for DirectX 10. If someone could provide a source confirming or denying it, it would be great. Also what is the guarantee offered. Will the output be exactly the same or just perceptually the same to the human eye?