Newer BIOS versions usually improve stability, fix bugs or add support for newer hardware. They mostly never remove support for older generation hardware unless specifically stated in the BIOS support page.The board is pretty neat for it's price. I know that B550 supports new series and 3000 series, what I'm not sure about is how the bios download sections have written 'no longer support to flash back to older bios' for their latest bios downloads. I'll have a 3600x and was wondering if flashing the latest BIOS for the A PRO will then stop supporting my cpu.
I read that Asrock has not yet released BAR support for some of their boards, that's why wanted to know from that guy if the B550m Pro 4 has it or not.
These B550 boards were launched with support for Ryzen 3xxx series out of the box & support for newer Ryzen 5XXX series processor was added later in the subsequent BIOS updates. These newer BIOS updates still contains code to support Ryzen 3XXX series so you can rest assured. In fact if you look at the CPU support list of your particular motherboard here https://www.msi.com/Motherboard/support/B550-A-PRO#support-cpu, you can see that Ryzen 3600 was been supported since version 7C56vA0, i.e. since the 1st version, whereas support for Ryzen 5600X was added later in version 7C56vA4. So, 3600 will always be supported unless specifically stated otherwise. Ideally you should update to version 7C56vA5 to add support for Re-size BAR function if you have a supported GPU.
Actually that is not really true. In fact almost none of the B550 or X570 motherboards have support for Re-size BAR out of the box despite them being PCIE gen 4. This feature was introduced with 5000 series processors & support for this has been added later via BIOS updates for both 5000 as well as 3000 series.As far as I know, all PCIe4 boards support rBAR put of the box, while older pcie3 boards require the manufacturer to issue a bios update to enable it