After receiving criticism from its fans and casual users, AMD has reversed its decision to not to enable Zen 3 and Ryzen 4000 compatibility with existing B450 and X470 motherboards. AMD has worked on it and came with the solution of the BIOS update but it will be a one-way path You can flash your motherboard to the new firmware, but you will not be able to flash it back to previous BIOS versions which mean that you will not be able to use the ryzen processors till the Zen 2 (3000 series) on the updated motherboard. To reduce the confusion, AMD’s intent is to offer BIOS download only to verified customers of 400 Series motherboards who have purchased a new desktop processor with “Zen 3” inside. The new BIOS revisions will enable the full functionality of Zen 3 processors, but you will still not gain access to the PCIe 4.0 interface on B450 and X470 motherboards. This also marks the end of the line for 400-series motherboards: AMD will not support future processors on the platform. AMD continues to recommend that customers choose an AMD 500 Series motherboard for the best performance and features with our new CPUs.The company also confirmed that Ryzen 4000 will land this year.