It's all about the memory bandwidth.

Apple M chips are slower on the computation that AMD chips, but they have soldered on-package fast ram with a wide memory interface, which is very useful on workloads that handle lots of data.

Strix halo has a 256-bit LPDDR5X interface, twice as wide as the typical desktop chip, roughly equal to the M4 Pro and half of that of the M4 Max.