An interesting revelation (from AMD’s official website) is that PCIe Gen 5 isn’t a mandatory requirement for B650 motherboards. All other AM5 chipsets, including the B650E, X670, and X670E, will feature Gen 5 support across the M.2 and/or the PCIe x16/x8 graphics slot. Board partners, however, can get away with a single PCIe 4.0 M.2 slot and a single PCIe x16 4.0 or dual x8 4.0 graphics slots on B650 motherboards.
The B650E offerings will come with quad-lane PCIe Gen 5 lanes for super-fast NVMe SSDs and a 16-lane or two eight-lane Gen 5 slots for discrete graphics. The X670, on the other hand, will support PCIe Gen 5 across one M.2 NVMe port and stick to Gen 4 across the graphics expansion slots. Like the B650E, X670E will feature PCIe 5.0 across both storage and graphics buses.