In the past, it was super easy to find a block diagram illustrating that architecture on the Web. For Windows 10, I can't find anything. I've found subsystem diagrams, Windows 7 or earlier ...

The diagram is not an official AMD one, however does seem to originate from a motherboard partner, and that does show it a... AMD X570 Chipset Blockdiagram Surfaces - Specs - PCIe 4.0 All The Way ...