Over at the chiphell forums, a block diagram leaked of the AMD X570 Chipset. The diagram is not an official AMD one, however does seem to originate from a motherboard partner, and that does show ...

It's clear already that Ryzen 3000 CPUs (Matisse) and the X570 chipset will support PCIe 4.0. The new diagram once again confirms that the processor will provide a total of 24 PCIe 4.0 lanes.