[solved] Main BIOS won't post. Backup BIOS works fine. How can I fix it?

Motherboard: Gigabyte Aorus GA-AX370-Gaming 5 (rev.1)
Main BIOS ver.: F6 (Agesa 1006)
Backup BIOS ver.: F3
OC: none

Problem: until a few hours ago my PC worked fine. when I turned it on again it froze on the desktop, right as Discord App was starting, no response at all.
Pressed the reset button on my case and then it wouldn’t post. no signal to both of my monitors. the error codes on the motherboard would cycle through some codes, then the LED on the AMD stock cooler flickered, error code cycle starts again, rinse and repeat.
Clear CMOS button didn’t do anything. BUT: when I flipped the switch on the BIOS-switch it worked fine with the backup BIOS (posting this from my PC).
I was able to confirm that it’s the main BIOS when I powered the PC off, flipped the switch back and tried to turn the PC on again -> error code cycle, no signal to monitors.

How can I fix the main BIOS? I keep reading the following procedure (and variations of it)

Method #1:

  1. Shut your PC down (if you’re reading this guide, than your PC isn’t working anyways)
  2. Hold the power button until the PC starts and shuts down again
  3. Press the power button again, your backup BIOS should kick in now and should re-flash the main BIOS if there’s anything wrong with it.

Method #2:

  1. Shut your PC down
  2. Hold the power AND the reset button for about 10 sec, than release.
  3. Backup BIOS should kick in anytime soon now.

but nowhere does it say in which position the BIOS switch has to be. I don’t know if it’s possible to corrupt the backup BIOS too if the switch is in the wrong position.

I also keep reading that the main reason for a corrupted BIOS is a failed BIOS update but I updated quite a while ago and it worked fine until today.

I did not OC the CPU and only set the RAM to XMP profile (which worked AFTER the update to ver. F6 (Agesa 1006)).

Only thing that comes to mind is that I installed MSI Afterburner today to change the GPU fan settings.

Thanks for any advice in advance!

The main way i know how to fix a failed bios is to boot into the backup bios and enter the bios flash util. change the switch to the main bios and flash it

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Should I get the newest BIOS version or step by step? (F3 -> F4 -> F5 -> F6)

does not matter. latest bios will be fine

Gonna try that now. Wish me luck.

good luck

BIOS doesn’t detect the USB flash drive and I noticed that autoexec.bat is missing from the flash drive after I booted into Windows again.

edit: might be due to the flash drive being NTFS, reformatted it and trying it again

Needs to be Formatted to a FAT file system. I always use FAT32 myself.

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Was able to re-flash the main BIOS thanks to @Dje4321’s instructions. Main BIOS is back in use and on the newest version again. Works fine.

Thanks!

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no problem. same thing works with single bios motherboards that have a removable bios chips

Glad you got it working! I wonder how it got corrupted?

No idea. I updated the BIOS to the newest version the same day I built the PC, which was a few weeks ago.
Used Q-Flash (download the update, put it on a flash drive, boot into the BIOS and select Q-Flash) and it worked fine. No idea what suddenly caused it to stop working. I used it ~6h before without any problems.

Do you have any power cables routed near your bios chips? The reason I ask is because when current passes through wire it creates a magnetic field, and magnetic fields have been known to corrupt things. It is very unlikely to actually ever happen, but I thought I would ask.

No. The only cable near them is the one for the AMD stock cooler LED.
I noticed those white marks on them today but the photo indicates that they’ve been there since day 1 (that’s when I took the picture).

That looks fine to me. It would be near impossible for it to happen even if you had cables laying right on them. Those white dots are there to either indicate chip orientation during assembly, or were put there to show they passed quality control. At least that’s my guess anyway.

Nice clean build by the way!

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Thanks!

The long LED cable is an eyesore, though.

Hello @TheDiddilyHorror I have the same motherboard and same issue you had. Was wondering if you could do a step by step for me on using the backup bios, switching to the main then re-flashing. I would really appreciate it as I am just learning into this side of things. Thanks for your time in reading this!

Lemme see if I can remember…
I think the method I used involved entering the backup BIOS and then flipping the switch back to the (corrupted) main BIOS before flashing the BIOS.
But I don’t remember if that was all to it or if I’m missing steps.

So…act with caution, I guess?

OK, I appreciate your time. I am viewing some vlogs on it however it is not the same mobo but I’ll run some trials and get there! Have a nice day!

duh, was right in the 2nd post.

So you download the BIOS from Gigabyte’s website and put it on a USB flash drive (which is formatted in Fat32, NOT NTFS. Restart PC, enter BIOS, go to the BIOS flash thing, flip the switch on the mobo back to the corrupted BIOS and flash it.

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