Hello.
I have B350 motherboard (Gigabyte a320m s2h v2 (and yes, it’s B350, not A320)) with latest bios (F55a, AGESA 1.2.0.7).
My current Ryzen 1200 works well on this board with this BIOS and Windows 7.
But after i replace it by Ryzen 5500 i have permanent BSOD during Windows booting: 0x000000A5 -This BIOS in this system is not fully ACPI compliant.
So, what can be a problem ? The BIOS is the same, but Ryzen 1200 works and Ryzen 5500 have a BSOD.
UPDATE: I have the same situation with Windows 7 installer. It loads initial files, after that it shows logo with progress bar and crashes with the same BSOD.
maybe you can find solution with help of experienced users;
had luck sofar with motherboards, a320, b450, x470, a300, all got running with windows 7 64bit, various processors (2600, 3600, 5600, a10-9700 (easy:) and now 3200g)
but it seems some newer boards are not so easy to treat for windows 7.