If you want to run an old AMD motherboard with a Ryzen 3000, you need a BIOS update. AMD will send you a Boot Kit with Athlon 200GE.
Ryzen 3000 on 400 motherboard only with BIOS update
With the new Ryzen 3000 processors, AMD has retained one feature: backward compatibility. So all new CPUs also run on (almost) any older motherboard of the first and second Ryzen generation. So if you only want to upgrade the processor, you can keep your motherboard and only do without features like PCIe 4.0 (and not necessarily even that). Thus the X470 motherboards in particular also form an important counterpart to the X570 motherboards. These only start at a good $160 and are anything but cheap. The most expensive models can also be purchased for over €700. Comparatively well equipped X470 motherboards are also a good alternative.
All you need is a BIOS update. Both B450 and X470 should then be compatible with the Ryzen 3000 processors. For X370 and B350 there are currently only beta BIOS versions, but they also work. For those who can do without PCIe 4.0, the now “old” motherboards are also an option for a new purchase. However, the old BIOS version can become problematic.
AMD lends Boot Kit for BIOS Update
AMD itself has a solution to this problem, just as they did when it switched from the first to the second Ryzen generation. The company sends a so-called boot kit to Ryzen 3000 purchasers who otherwise have no way of performing a BIOS update. For example, it is conceivable that a motherboard with an outdated BIOS has been purchased or your own Ryzen 2000 processor is defective. The Boot Kit contains an AMD Athlon 200GE, which is used to update the BIOS and is shipped by AMD free of charge – but with conditions. Thus, you have to verify with photos of the processor and motherboard that you have actually bought a Ryzen 3000 processor. In addition, you must first try to solve the problem through the manufacturer of the motherboard. After that AMD will send the Boot Kit for Ryzen 3000, which has to be returned within 30 days and the company will also pay for the return shipment.
Interested parties can contact the company via an online form on the AMD support page to obtain the Ryzen 3000 Boot Kit. AMD then checks the prerequisites. The service will probably also be available for Europe, but currently the German AMD site still refers to the old upgrade kit for Ryzen 2000.