[GUIDE] Flash AMI BIOS With Different ROM ID on ASUS Motherboard

There are very few scenarios where you need to flash firmware from a different model, nor do I recommend you do it, as 95% of the time it will result in a brick. Today, however, I needed to as part of another project I’m working on (had to hotflash a BIOS chip from a different motherboard). It was quite tricky to get it to work, but for anyone else getting a “ROM ID doesn’t match” or similar error and you KNOW FOR CERTAIN that you have the correct ROM (or you are also trying to hotflash a different board’s BIOS chip), read on.


  • ASUS motherboard using an AMI APTIO IV or APTIO V BIOS.
  • The .CAP version of the BIOS you want to flash.
  • An MS-DOS bootable USB or equivalent (use Rufus if you need to make one)
  • AMI Firmware Update APTIO IV or V, whichever your board uses (or download both)
    • You can get APTIO IV HERE
  • ASUS BUPDATER.EXE. I found mine in the downloads section for my host motherboard.


  1. First & foremost, it would be best for you to make a backup in case you make a mistake.
  2. Extract APTIO Firmware Utility somewhere then navigate to \afu\afudos and extract (again) AFUDos.
  3. Copy AFUDOS.EXE to your DOS bootable USB (do both versions if you’re unsure, I named one AFUDOS4.EXE and AFUDOS5.EXE).
  4. Copy BUPDATER.EXE and your BIOS.CAP file to your DOS bootable USB.
  5. Make sure you have Legacy Mode enabled in the BIOS and boot from the USB.
    • After MS-DOS or equivalent has booted, this would be a good opportunity to carefully switch BIOS chips (only if you are using this guide to hot-flash a different chip).
    (These commands might also run together as “AFUDOS.EXE BIOSNAME.CAP /X /B /P /N” but I’m just posting my exact steps for how I got it working).
    If you are using an Intel motherboard you might also have to do AFUDOS.EXE BIOSNAME.CAP /X /ME /MEUF or something (I was using AMD, so it wasn’t necessary).
  9. If all those succeed, run BUPDATER.EXE /G
    In the top left corner it should now show your new ROM info.
    Select your BIOSNAME.CAP and hit enter, follow the prompts.
    * This step may be redundant, but mine wouldn’t POST without doing it for some reason.
  10. After this completes, voila, you now have a different ASUS BIOS on your BIOS chip and you didn’t need to buy a flash programmer (but I really should one day).

If anyone tries this with an Intel motherboard and the process needs to be amended, please feel free to add on to this guide.