The first signs that AMD might be building a specialized gas pedal for cryptocurrency mining appeared back in October 2020. A Linux kernel update added a new Navi 10-based gas pedal with ID 731E. This card, as clearly spelled out in the description, will not support DCN (Display Core Next) and VCN (Video Core Next), which means that it is a graphics processor without image output capability.
This graphics card can be used either to accelerate computing in clusters or for cryptocurrency mining. According to a new patch on March 3, AMD has created the Navi 12 GPU, which also lacks VCN, that is the ability to output an image. The latest GPU comes just after NVIDIA made an announcement about its mining solutions, which are expected to launch later this month. Interestingly, Navi 12 is not available in any free-market Radeon graphics card. It was designed specifically for the Apple Mac as the Radeon Pro 5600M. It is the only Navi 1X GPU with HBM2 memory. There are no mining tests available for it, so it's hard to predict how well it will perform in cryptocurrency mining.
In terms of specifications, both Navi 10 and Navi 12 offer 2,560 stream processors (40 processing units). Navi 10 is available with 8 GB of GDDR6 memory, while Navi 12 has 2 HBM2 memory stacks of 4 GB. The GDDR6 memory has a bandwidth of 448 Gbps, while the Navi based on HBM2 can offer 394 Gbps. If we believe the words of a rather reputable informant Komachi, AMD started preparing variants of the RX 5700 XTB, RX 5700 B and RX 5500 XTB specifically for cryptocurrency, no later than last November. These could be working names for the new cards, but it's unclear if AMD would want to use the Radeon brand for such gas pedals.