A ghost from the past emerged on a Reddit thread (opens in new tab) the other day. A user has managed to get his hands on a Radeon Pro prototype that leverages the entire Vega 20 die.

AMD has produced many graphics cards and accelerators based on the Vega 20 silicon. But only the more exclusive and niche models came with the fully-enabled Vega 20 die, which houses 64 CUs, equivalent to 4,096 shading units. The small list includes the 2018-era Radeon Instinct MI60, which targets the AI and deep learning market, plus the Radeon Pro Vega II and Radeon Pro Vega II Duo, which wound up in select Mac Pro machines. Sadly, the retail market got to reap the full benefits of what Vega 20 had to offer.

The mysterious Radeon Pro from the Reddit thread sports the same aesthetics as the Radeon Pro V420, a professional-grade graphics card that also never made it to the market. Photographs of the PCB reveal the big Vega 20 silicon, which measures 331 mm², with four stacks of high-speed HBM2 memory. In addition, the prototype features one 8-pin PCIe power connector and a 6-pin PCIe power connector, a suitable configuration for up to 300W.

Since it’s unreleased hardware, GPU-Z had difficulty figuring out the Radeon Pro graphics card. However, according to the software, it has the same device ID as the Radeon Instinct MI60. In addition, the utility reports SK hynix as the manufacturer of the HBM2 memory, but in reality it’s Samsung.

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According to the owner, the Radeon Pro graphics card comes with two different sets of firmware. The primary firmware has a higher power limit with 32GB of 1,600 Mbps memory, whereas the second firmware features a more modest power limit with a memory quota of 31.984GB. In addition, the graphics card sports the typical blower-style cooler, which looks pretty good and even has a bit of RGB lighting to it. The Redditor reported temperatures less than 80 degrees Celsius
under load, with the cooling fan hitting speeds of 3,800 RPM. For reference, the cooling fan has a maximum rotational speed of 5,000 RPM.

The Radeon Pro prototype hits 1,700 MHz, so it’s well within the range of the other Vega 20-powered SKUs. The Radeon Pro Vega II tops out at 1,720 MHz, and only the Radeon Instinct MI60 flaunts a 1,800 MHz boost clock speed.

Performance could be better, in part because it’s a prototype and needs proper software-level support. As a result, the Radeon Pro graphics card doesn’t perform 100% during real-world tests. Nonetheless, it delivered a double-precision performance of up to 6.4 TFLOPs, around 14% slower than the Radeon Instinct MI60.

It remains a mystery why AMD backpedaled and didn’t launch the Radeon Pro V420. It would have been a very competitive professional graphics card at the time.