@
CaseySJ
I've seen many people discuss in this thread that the Z390 Designare Capsule BIOS cannot be Downgraded. In Fact It Can Be Reverted. I wanted to share a short Guide that I posted on another site awhile back to show you how.
I hope this helps some people out, but please be careful by following it closely! Of course other motherboards can be downgraded in this fashion with the tool I've included (and specific versions of it), but I am not going to talk about this here.
This guide is for those who have updated their Gigabyte Z390 Designare to a later BIOS with a capsule and want to Revert to an earlier BIOS but can’t.
<It’s possible to downgrade using Intel Flash Programming Tool.> 
For Z390 Designare you will need the Intel FPT_v12.0.x.zip That I Will Include Below.
Inside each archive are UEFI, DOS, Windows 32-bit and 64-bit versions, you can use the same commands for each version. I will provide you with 2 different methods to revert the bios back to a previous one. Myself, I have only done the first method.
WARNING: Unlike Qflash, FPT will not check if you are flashing the correct BIOS to a matching motherboard so you can brick your motherboard if you cross-flash the wrong BIOS! Make Sure to Flash the Correct Compatible Bios!
2ND WARNING: Your motherboard has an Intel Gigabit Ethernet Adapter(s), you can overwrite (erase) its MAC address(es) with FPT causing it to no longer function! Although the MAC address(es) may be recoverable, (I will not discuss how here), it is a big hassle that you will want to avoid. You will know if you have erased them if they display 888888888788 as the MAC address.
(Yep, Oh $hlT!) ↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑
DISCLAIMER: There is always a risk when flashing the firmware of any motherboard. You must decide if you think the risk is worth it - if you don’t know how to recover your motherboard from a bad flash then I don’t recommend that you attempt a BIOS downgrade. I am not responsible for any problems that arise from your actions. While I have performed Successful Downgrades on my Gigabyte Z390 Designare motherboards, I cannot 100% guarantee that you will not run into problems. Please read the Entire guide before you even attempt a downgrade.
BEFORE YOU ATTEMPT TO DOWNGRADE YOUR BIOS, YOU SHOULD WRITE DOWN THE MAC ADDRESSES OF ANY INTEL GIGABIT ETHERNET ADAPTERS IN YOUR SYSTEM.
You can find your Intel MAC address(es)
several different ways.
I. Boot into the BIOS and look under System Info –> LAN MAC Address (ALSO): System Info –> LAN2 MAC Address
II. In Windows open a command prompt (cmd) and type “ipconfig /all” then look for “Ethernet adapter Ethernet” then “Physical Address”, you will need to copy and save the MAC address(es) somewhere just in case you ever need.
III. If your adapters are currently plugged into a network, Control Panel –> Network and Sharing Center –> Change Adapter Settings –> double-click on ‘Ethernet’, then click ‘Details’ and look for ‘Physical Address’.
BIOS Downgrade Method 1: Using 64-bit FPT from a command prompt in Windows
Download FPT_v12.0.x.zip and create a folder on C Drive called FPT. Copy the contents of the WIN64 folder from the zip archive into the new FPT folder on C Drive.
Open an elevated command prompt (as administrator) and navigate to the FPT folder
Make a backup of your current BIOS chip using the command;
fptw64 -d bios.bin
You should see “FPT Operation Successful”.
To check your motherboards Intel ethernet adapters and at the same time backup the MAC address(es) type the following commands;
fptw64 -gbe -d gbe.bin
You should receive the following message;
8KB of 8KB - 100 percent complete.
FPT Operation Successful.
NOTE: If you open gbe.bin in a hex editor, (Such as WinHex), you can find your MAC address(es).
Copy the BIOS file you want to flash into your FPT folder.
Use the following commands to flash the entire EEPROM (all BIOS regions are overwritten i.e. Descriptor, GbE, ME and BIOS);
fptw64 -SAVEMAC -f .bin (example: fptw64 -SAVEMAC -f Z390DESI.f9i)
The command -SAVEMAC will retain your Intel MAC address(es) so don’t leave it out!
The Following Command Will Not Save Your MAC ADDRESS;
fptw64 -f .bin <
SO DON’T BE A DUM DUM AND DO THIS!!!
Once the flash operation says it has completed successfully type the following command to IMMEDIATLEY reboot and load the BIOS you just flashed;
fptw64 -greset
Note: that your PC will restart instantly without any warning as though you have pressed the reset button.
Go into BIOS and check the BIOS version under System Info, it should be the BIOS You Just Flashed.
BIOS Downgrade Method 2: Using the DOS version of FPT from a FAT32 formatted bootable USB stick. (Although this method should work just fine, I Have Not Personally Tested).
Download Rufus and use it to create a DOS bootable USB stick with FreeDOS or MSDOS.
Download the FPT tool and copy the file FPT.exe from the DOS folder in the zip archive onto the USB stick and also copy the BIOS you want to downgrade to.
Boot into FreeDOS or MSDOS (CSM will need to be enabled in your BIOS)
Make a backup of your current BIOS chip using the command;
fpt -d bios.bin
You should see “FPT Operation Successful.”
To check your motherboards Intel ethernet adapters and at the same time backup the MAC address(es) type the following commands;
fpt -gbe -d gbe.bin
You should receive the following message;
8KB of 8KB - 100 percent complete.
FPT Operation Successful.
NOTE: If you open gbe.bin in a hex editor (Such as WinHex) you can find your MAC address(es).
Again, make sure the BIOS file you want to flash is in your FPT folder.
Use the following commands to flash the entire EEPROM (all BIOS regions are overwritten i.e. Descriptor, GbE, ME, BIOS) ;
fpt -SAVEMAC -f .bin (example: fpt -SAVEMAC -f Z390DESI.f9i)
Again, -SAVEMAC will retain your Intel MAC address(es) so don’t leave it out!
Once the flash operation says it has completed successfully type the following command to IMMEDIATLEY reboot and load the BIOS you just flashed;
fpt -greset
Note:
Your PC will restart instantly without any warning as though you have pressed the reset button.
Go into BIOS and check the BIOS version under System Info, it should have reverted to the BIOS you just flashed.
