This has been surfaced a lot in the recent discussions and I gave it a go yesterday. This one is so so so good. Not only the black market which I think is totally OK for NVIDIA to do, but the damn guy who soldered more RAM to a 4090. That was worth every second of my time.

Yeah, that was quite impressive!

There are (were?) kits available in China where one would salvage the GPU chip and VRAM from a 4090 card and solder them to a new board, then add an additional 24GB.

If I knew anyone who could do the work safely, I'd happily have my 4090 converted.

https://gpusolutions.net/ lists three different ram upgrades for different nvidia cards.