This is only supported with the previous generation NVidia 3090, it is apparently possible to combine two 3090s with 24 GB VRAM and 'fuse' them with NVLink to a

This is only supported with the previous generation NVidia 3090, it is apparently possible to combine two 3090s with 24 GB VRAM and 'fuse' them with NVLink to act as a single high-powered GPU with 48 GB VRAM combined. NVidia no longer supports this for the 40-series, I think this is because they want anyone interested in using their GPUs for LLMs to buy the pricier models with more VRAM.