90MB14I0-M0EAY0, Asus AMD B550 (Ryzen AM4) micro ATX motherboard with dual M.2, PCIe 4.0, 1 Gb Ethernet, HDMI/D-Sub/DVI, SATA 6 Gbps, USB 3.2 Gen 2 Type-A, and Aura Sync RGB headers support
AMD has decided to block PCIe 4.0 support on all pre-X570 motherboards | PC Gamer
Amazon.com: MSI B550-A PRO ProSeries Motherboard (AMD AM4, DDR4, PCIe 4.0, SATA 6Gb/s, M.2, USB 3.2 Gen 2, HDMI/DP, ATX) : Electronics
PCIe 4.0: Everything you need to know, from specs to compatibility to caveats | PCWorld
Buy ASRock B550M Pro SE AM4 DDR4 SATA 6Gb/s 1 PCIe 4.0 x16 Micro ATX Motherboard - Netcodex.ph
ASUS AMD AM4 ROG X570 Crosshair VIII Hero (Wi-Fi) ATX Motherboard - Newegg.com
Asus Rog Strix B550-A Socket AM4, Full Connectivity, PCIe 4.0 Ready, A – EasyPC
New Amd Ryzen 7 5700g R7 5700g + Asus Rog Strix B550 A Gaming Amd Am4 Gaming Motherboard Pcie 4.0 All New But Without Cooler - Motherboards - AliExpress
Existing AM4 motherboards may support PCIe 4.0 - OC3D
AMD Confirms PCIe 4.0 Not Coming to Older Motherboards (X470, X370, B350, A320)