From a reliable source
The release of Nvidia video cards of the Blackwell generation is still quite far away, but gradually new details about these solutions are appearing on the Internet. Now it has become known what kind of bus the non-top solutions will get.
Insider kopite7kimi says that adapters based on the GB203 GPU will receive a 256-bit bus. Let us remember that the current AD103, on the basis of which the GeForce RTX 4080/4080 Super and RTX 4070 Ti Super 3D cards are created, has a similar characteristic.
GPU GB205, in turn, will offer a 192-bit bus. It’s impossible to draw an analogy here, since the Ada Lovelace line does not have the AD105 GPU — there are AD104 and AD106. The first has a 192-bit bus, and the second — 128-bit. That is, probably, GB205 will be a successor specifically for AD104. That is, the GeForce RTX 5070 and RTX 5070 Ti video cards will apparently be based on it.
Presumably, GB203 will receive 96 SM blocks, that is, if the ratio remains the same, 12,228 CUDA cores. By comparison, the AD103 has 10,240 CUDA cores.
Insider kopite7kimi was the first to accurately describe the parameters of GeForce RTX 30 cards, and he also described RTX 40 cards more than once. Overall, it is one of the most reliable sources in this segment.