Flash method in EFI Shell:
1. copy xxxx.bin and AfuEfix64.efi to root directory.
2. AfuEfix64 xxxxx.bin /p /b /n /k /l /x
4. BIOS not support downgrade flash action due to security

Non-boot BIOS is written as is (raw) - no RomID check, no variables preserve/update.
AMI recommend flashing RAW image of non-booting CPU to be used only in the case of empty BIOS part or if the previous booting image is corrupted and needs fresh update.

1. Milan CPU installed on system. 

 Flash Milan BIOS 
 Updating Milan BIOS using 32MB file 
 AfuEfix64 Output_32.bin /p /b /n /k 

 Flash Rome (non-boot) BIOS (Using AFU - 5.14.02.0026 or newer with Milan 0ACOU010 or newer) 
 Flash Rome BIOS using 32MB file 
 AfuEfix64 Output_32.bin /p /b /n /k /atr /SSB:{NONBOOT16M} 

2. Rome CPU installed on system. (Rome BIOS should support dual image update and set to BOTTOM 16M) 

 Flash Rome BIOS 
 Updating Rome BIOS using 32MB file 
 AfuEfix64 Output_32.bin /p /b /n /k 

 Flash Milan (non-boot) BIOS 
 Flash Milan BIOS using 32MB file 
 AfuEfix64 Output_32.bin /x /atr /SSB:{NONBOOT16M} 

Note: 
Due to limitation #1 user will be presented following dialog in case flashing non-boot BIOS: 
WARNING !!
 The ROM file information does not match with the system BIOS!
 If forcedly update BIOS, it may destroy the System BIOS!
 We strongly do not suggest to flash the BIOS!

 Press "E"- This option will update entire ROM and exit.
 Press "A"- This option will be no ROM update.
 Press "F"- This option will be forcing to follow the command by user
   provided.

Please select one of the options:e

To use AFU in batch file option /RLC:e can be added to not require user input: 
 AfuEfix64 Output_32.bin /x /RLC:e /atr /SSB:{NONBOOT16M} 