I bought an A12-9800 APU processor for my PC, which has an A320M-K motherboard. I put in the chip and it failed to boot. I found out afterwards that the current bios doesn't support it. I reverted the bios to and older version that is supposed to have support for it, but when I put the chip back in it still did not boot up. How can I fix this?
The problem with the 300 series Motherboard BIOS is that they are not very large. So to make the latest Ryzen processor compatible they needed to delete older processors in the BIOS to make room.
Thus BIOS Version clearly states that 7th Generation processors like yours will be removed as being compatible or support while BIOS version 5606 should work be the last BIOS to work with your A12 processor.
Your Motherboard's CPU SUPPORT LIST mentions this also: https://www.asus.com/us/Motherboards-Components/Motherboards/PRIME/PRIME-A320M-K/HelpDesk_CPU/
Now as to revert back to an older version may be impossible. I also have a ASUS Motherboard and once you reach a certain version you can't revert to an older version. Your motherboard might be the same way.
You can open a ASUS Support Chat and asked them if it is possible to revert to an older version but I have a feeling they will say you can't but no harm in trying.
Good luck. Because you will either have to upgrade to a processor that is now supported by your Motherboard or replace your motherboard. Only way to make you Motherboard support your A12 processor again is to physically replace the BIOS chip with one with an older BIOS installed if you can't revert to an older version.
When you tried to revert to an older BIOS version did it say it was successful when it completed?
If your not sure I would just temporarily borrow an Ryzen supported processor and see if it actually did revert to an older BIOS version. I bet it didn't.
Deleted. elstaci covered it.
On your Gigabyte Motherboard can you downgrade your BIOS version by any chance or is it like my Asus Motherboard where you can't downgrade once you reach a certain version level?
Well it's 2020 product (Ryzen 3/4/5xxx support (no athlon)), no mention of downgrade lockout on mobo site.
Looking at my Asus BIOS download page it doesn't mention about not able to downgrade to an older version but I do see this:
In BIOS version for my Motherboard 2816 or older you don't need to rename the BIOS file to "CAP"
But in BIOS Versions starting at 3001 or newer you must rename the BIOS file to end in "CAP" to upgrade.
I remember that once I upgraded to version 3001 I was unable to downgrade my BIOS below 3001 version anymore. Another User also verified this here at AMD Forums in the past.
So I guess when you are trying to downgrade the BIOS version without renaming it "CAP" it won't accept it thus locking you out from downgrading the BIOS to an earlier version that doesn't require you to rename the file to "Cap".
EDIT: @man_with_mid_pc Looking at your BIOS Download page it seems like you should be able to downgrade your BIOS. Maybe you didn't do it correctly.
Are you using Asus EZ Flash plus did you update the Motherboard's CHIPSET drivers before upgrading to the last BIOS Version. In earlier BIOS version Asus mentions it recommends you update the Asus CHIPSET first before upgrading the BIOS to a new version.
Best to ask Asus Support Chat to see if the BIOS is locked after a certain version or not.