Motherboard vendors have started releasing BIOS updates to patch in support for the upcoming Zen 3 CPUs. The latest updates for ASUS and ASRock boards based on the X570 and B550 chipsets include support for not only the A0 and B0 stepping of Vermeer (Ryzen 4000 CPUs) but Cezanne as well.
In the above screenshot, you can see the two entries for the A0 and B0 stepping of the Ryzen 4000 desktop CPUs. These were released during the last week of Jan and July, respectively.
Here, you’ve got the update including preliminary support for the Cezanne chips (Ryzen 5000 APUs). These parts will be based on the Zen 3 cores, but continue to use an enhanced form of the GCN-based Vega GPU core. Vermeer is slated to launch in October/November while Cezanne will land in the second half of 2021 for notebooks and desktops.