Put the bios on a flash drive, and use QFlash, I used a flash drive to do mine.
With this utility, you can access Q-Flash by either pressing <End> key during the POST or pressing the <F8> key in BIOS setup menu. No need to enter operating systems like MS-DOS or Windows first. Caution
Before using Q-Flash utility, go to GIGABYTE website to download the latest compressed BIOS update file that matches your motherboard model. Extract the file and save the new BIOS file to your floppy disk, USB flash drive, or hard drive. And be noted that the USB flash drive or hard drive must use FAT32/16/12 file system.