You'll need a USB flash drive, the Rufus tool, the DOS FPT files and any D3H BIOS file.
Rufus:
https://rufus.akeo.ie/
BIOS:
http://www.gigabyte.us/Motherboard/GA-Z77-D3H-rev-10#support-dl
Use Rufus to create a FreeDOS bootable USB drive.
Extract the FPT executable (fpt.exe) and the unzipped BIOS file to the USB drive's root.
Boot to the USB stick (F12 on boot)
From the DOS prompt, run:
a:> fpt.exe -f <bios-filename>
Hit Y when prompted.
FPT will flash the BIOS from the DS3H to the D3H.
Turn off the PC when the flash is done. Clear the BIOS with the CMOS clear jumper.
Power on the MB and press DEL to get into the BIOS.
Notice the 3D-BIOS screen shows a D3H motherboard instead of the DS3H.
If you want to switch back to the DS3H BIOS, press CTRL-F10 during boot... the backup BIOS will revert back to the DS3H.
