Some ASUS X470 and B450 Motherboards Support PCIe 4.0 | eTeknix
Amazon.com: ASUS AM4 TUF Gaming X570-Plus (Wi-Fi) AM4 Zen 3 Ryzen 5000 & 3rd Gen Ryzen ATX Motherboard with PCIe 4.0, Dual M.2, 12+2 with Dr. MOS Power Stage : Everything Else
ASUS PRIME B660M-A D4 Micro-ATX Motherboard Intel12th Gen Socket LGA 1700 Supports Max 128GB DDR4-5333 PCI Express 4.0 2x M.2
AMD confirms lack of PCIe 4.0 support on older motherboards
Impact of PCI-E Speed on Gaming Performance | Puget Systems