Gigabyte's latest BIOS update enables PCIe 4.0 support on its AMD X470 and B450 motherboards - NotebookCheck.net News
ASRock > B450 Steel Legend
Amazon.com: ASUS ROG Strix B450-F Gaming II AMD AM4 (Ryzen 5000, 3rd Gen Ryzen ATX Gaming Motherboard (8+4 Power Stages, HDMI 2.0b/DP,2 x PCIe 3.0 x16, USB 3.2 Gen 2 Type-C, BIOS