Looking at the diagram, we see the CPU serving up 24 PCIe 4.0 lanes, with 16 of them jettisoned to two PCIe x16 slots for graphics cards. Those slots can be configured as either PCIe 4.0 x16 or x8/x8.

Some interesting things can be read from the block diagram otherwise, like the name of the chipset being Valhalla, lol. Next, to 16 PCIe Graphics lanes, 4 lanes are allocated to one M.2 NVMe slot ...