AMD was the first company to support the PCIe 4.0 protocol in its processors and accompanying motherboards. However, according to the latest information coming from the recent Gigabyte hack that already produced a plethora of new information, AMD will not bring support for PCIe 5.0 to its forthcoming socket AM5 motherboards, at least not initially.
According to TechPowerUp, which got ahold of Gigabyte's leaked documents, AMD decided to stay off the PCIe 5.0 wave with its upcoming AM5 CPU socket designed for its codenamed 'Raphael' processors.
The diagram below shows that AMD has given socket AM5 as many as 28 PCIe lanes. And those lanes run the PCIe 4.0 version protocol, which is the standard protocol today. Out of 28 lanes, 16 are devoted to the PCI express slot for graphics expansion, four for an M.2 SSD, four lanes for SATA expansion, and the remaining four for chipset communication with the socket.
The surprising bit is that AMD is falling behind Intel in the interconnect space. At yesterday's Intel architecture day, the company revealed that the upcoming Alder Lake series of processors will deliver PCIe 5.0 connectivity. Expected to be a competing product with AMD's Raphael, it will certainly boast a newer communication standard for higher-speed communication between PCIe devices.
That, of course, doesn't mean that Intel will force its OEMs to integrate PCIe 5.0 standard. Just because the chip is capable of supporting PCIe 5.0, doesn't mean that the motherboard is as well. The newer Gen5 protocol will require thicker boards for better wiring and more retimers/redrivers in order to carry the speed, so it is possible that the Gen5 protocol will be reserved for some higher-end products like the Z-level chipsets from Intel.
It is an interesting time to see how AMD and Intel play out the whole situation, and it will be interesting to learn why AMD opted to only support PCIe 4.0. The EPYC Genoa lineup does support the Gen5 standard, so it's curious that it appears to be segregating PC and enterprise users with I/O connectivity options. We can expect to hear more about it once AMD Raphael processors launch.