https://wccftech.com/gigabyte-bios-update-pcie-4-am4-motherboards-amd-ryzen-3000-cpus/

While AMD board partners are readying a new generation of X570 chipset powered AM4 boards for the 3rd Generation Ryzen processors, it looks like the latest BIOS for existing AM4 boards would be opening support for PCIe Gen 4.0 when paired with the upcoming Ryzen processors.

The AMD X570 platform will be the first fully PCIe 4.0 compliant mainstream platform but existing AM4 motherboards such as the ones based on the X470 and B450 chipset would also be open to supporting the new PCIe standard when paired with a new Ryzen 3000 series processor & updated to the latest BIOS.