Last week, I installed OpenCore based on someone's Github Repo on my GA-Z97X-UD7 TH rev 1.0. Later, I found out the BIOS entered black screen with flashing underscore every time I wanted to access the BIOS menu after I installed macOS with OpenCore. I didn't realized that it's OpenCore corrupted the BIOS as it could still boot my Windows and macOS (OpenCore), so I simply cleared the CMOS, thinking I would bring back the BIOS menu but it didn't. After I cleared the CMOS, it gave me back screen and won't boot any OS (I assume it's stuck at the BIOS reset warning menu and won't auto load any boot device).

Unfortunately, what's worse was that I just switched to the boot with backup BIOS and then kept using it for another week until I realized it also corrupted my backup BIOS in the same way (now with both BIOS corrupted). I searched with Google and found many people mentioned this OpenCore bug 1-2 years ago on Tonymacx86, reddit, and other forums. At this point, it's too late for me to realize that it's OpenCore corrupted my BIOSes as I've also reset the CMOS with the backup BIOS. (I could have reflashed the BIOS in Windows or DOS if I didn't reset the CMOS.)

Yesterday, I unsoldered both chips and flashed them with CH341A as I couldn't get CH341A detect both chips when they are soldered on the MB. However, it's in the same infinite reboot loop after I flashed the chips and soldered both back.

I've tried flashing the chips with the stock BIOS downloaded from Gigabyte website, and I've also tried flashing the stock BIOS with the GbE region replaced from the BIOS image I backup from the corrupted BIOS to transfer the GbE MAC address. However, both gave me the infinite reboot loop (switching between the main and backup BIOS).

I also suspect it might has something to do with the SERG1,SERG2,SERG3 of MX25L12873F as it gave me error when tried to erase the chips before. I had to "unprotect" the chips with ASProgrammer.exe or NeoProgrammer.exe before I could flash the chips. After flashed both chips with NeoProgrammer (because the CH341A.exe rev 1.29 and rev 1.4 won't flash the chips but showed timeout error every time I wanted to flash the chips), I checked the SERG in ASProgrammer, the main BIOS chip gives me SERG1=0x40, SERG2=0xFF, and SERG3=0xE7; the backup BIOS chip gives me SERG1=0x40, SERG2=0xFF, and SERG3=0x07.


TL;DR: What could I do to flash both the main and backup BIOS chips (MX25L12873F) if I have tried flashing both with CH341A and it didn't work? I have checked the CH341A has successfully flashed both chips; however, after I soldered both chips back, it was still in the infinite reboot loop. I have attached the BIOS images here:

https://drive.google.com/file/d/1z1et2RW...iew?usp=sharing
Z97XUD7TH.F7a is the stock BIOS from the manufacturer website.
Z97_backup.bin is the corrupted BIOS I backup with CH341A.
fix.bin is made from the stock manufacturer BIOS (Z97XUD7TH.F7a) with the GbE section replaced from Z97_backup.bin through UEFITool.app.


Edit by Fernando: Thread title specified, shortened and customized

so to be clear there is no backup of your bios before the mod? one thing that came in my mind is getting a used gigabyte h81 motherboard, then use intel fpt -f fix.bin to flash the fix.bin file, shut it down and desolder h81 chip, put it in your z97, and see if it boots.

You should've dump the motherboard bios using intel fpt or your progammer since it contains all the value you needed when everything didnt went well.. also afaik before skylake, gigabyte motherboard bios chips could operate independently, that if you flash the bios update, the backup bios wont get any write (depends, you could see in intel FIT that if the flash number is 1 or 2, if it's 2 then all of your bios chips will get flashed). and the way to force backup bios to recover main bios only (not using b_bios for boot) is by press and hold power + reset for 11 seconds (it will power on, and off) , release it, and power it on, that way you will have a message to restore main bios using backup bios.. atleast on gigabyte motherboard before skylake, as it worked on my b75 and my friends b85 gigabyte motherboards.