Rumors have a 5090 with GDDR7 and a 384-bit bus. Micron has GDDR7 modules on their roadmap as 2GB and 3GB. This means that the memory configurations for 2GB modules will be 24 or 48GB, and with 3GB modules it will be 36GB or 72GB.

32GB would imply it’s a 256 or 512-bit bus, neither of which are very likely for a xx90. I could see them maybe going as low as a 320-bit bus for 30GB. Even 33GB with a 352-bit bus is more likely.

The 5080 will be another thing, 24GB would imply a 256-bit bus with 3GB modules. Nvidia has been all over the map with the xx80 memory width, so it will be anyone’s guess. If they prioritize memory bandwidth and use a 320-bit bus, a 20GB card is most likely.

GDDR prevents having arbitrary memory sizes.

There aren’t a lot of places AMD can use 14nm anymore. They’re locked into a wafer supply agreement with GlobalFoundries until 2025 and GF abandoned development on their sub-14/12nm nodes.

Since AMD is moving even IO dies to more advanced nodes, they’re running out of places where they can use GlobalFoundries.

AMD got a lot of AI-related IP when they made the acquisition of Xilinx. It’s just a matter of them dedicating the die space to it.