Earlier quoted context omitted.
True, and 3990x supports more than 256, but not in practice (motherboards)
The (bit of) article mentioned 2T, but the thing that was interesting was the 8 channel memory. My current TR4 boards are doing quad, so 2 banks of 4 slots. Sounds like a single set of 8... so wonder if this is a potential BIOS update on the sTR4 or if there is a new chipset on route?
Your 4 channels with 2 slots each have the 4 channels daisy chained to 2 slots, but they are just 4 channels. With 8 channels and 2 slots per channel you can have 16 slots, with 32 GB unbuffered (regular) DIMMs you are limited to 512 GB of RAM, for 2 TB you need registered or load reduced RAM.