It uses LPDDR5X-8000, with a 256-bit memory interface (double in comparison with standard desktops).
8 GHz x 32 bytes = 256 GB/s
This has been known for a long time.
What annoys me is that AMD does not say whether the Zen 5 cores of Strix Halo have full vector processing pipelines, like Granite Ridge and Fire Range, or they have the narrow pipelines of Strix Point and Krackan Point.
Various leaks have claimed that some products would ship with DDR5-8533 which is 266GB/sec. I wouldn't be surprised if a range of frequencies ship with the 1st gen devices.
Maybe even a SFF sized motherboard that allows CUDIMMs, which is a nice fit since each CUDIMM is 128 bits wide.
Zen 5 CPU, RDNA 3.5 GPU, and XDNA 2 NPU. No word on process nodes.