According to Gigabyte’s Leaked Socket AM5 documentation.
Yet more disappointing news … I was expecting AMD’s Upcoming Raphael will support PCIe Gen 5, but apparently not.
Taken from TPU … AMD might fall behind Intel on PCI-Express Gen 5 support, say sources familiar with the recent GIGABYTE ransomware attack and ensuing leak of confidential documents. If you recall, AMD had extensively marketed the fact that it was first-to-market with PCI-Express Gen 4, over a year ahead of Intel’s “Rocket Lake” processor. The platform block-diagram for Socket AM5 states that the AM5 SoC puts out a total of 28 PCI-Express Gen 4 lanes. 16 of these are allocated toward PCI-Express discrete graphics, 4 toward a CPU-attached M.2 NVMe slot, another 4 lanes toward a discrete USB4 controller, and the remaining 4 lanes as chipset-bus.
Socket AM5 SoCs appear to have an additional 4 lanes to spare than the outgoing “Matisse” and “Vermeer” SoCs, which on higher-end platforms are used up by the USB4 controller, but can be left unused for the purpose, and instead wired to an additional M.2 NVMe slot on lower-end motherboards. Thankfully, memory is one area where AMD will maintain parity with Intel, as Socket AM5 is being designed for dual-channel DDR5. The other SoC-integrated I/O, as well as I/O from the chipset, appear to be identical to “Vermeer,” with minor exceptions such as support for 20 Gbps USB 3.2×2. The Socket has preparation for display I/O for APUs from the generation. Intel’s upcoming “Alder Lake-S” processor implements PCI-Express Gen 5, but only for the 16-lane PEG port. The CPU-attached NVMe slot, as well as downstream PCIe connectivity, are limited to PCIe Gen 4.