How does gigabytes dual bios know when the main bios is broken?

[Maximilian]

Does the backup chip wait a certain amount of time for a POST confirmation before kicking in or is there a 3rd chip controlling this that signals the backup chip to kick in? How does this feature actually work?

The main bios cant have anything to do with it i assume because if its knackered with a bad flash etc it cant be relied upon for anything.

 

[VirtualLarry]

Generally, this is accomplished via a checksum routine, and watchdog timers. If the CPU doesn't checksum and acknowledge a GPIO port within a few ms, then the watchdog timer circuitry resets the processor, and flips an address bit on the BIOS rom(s).

 

[Magic Carpet]

Hate Gigabyte for that... it used to reject my custom bios for that exact reason Larry pointed out ^.

 

[Maximilian]

Hmm sounds good, if i manage the impossible and instead of flashing an upgraded bios i flash a bon jovi mp3 to it or something it should be fine with a gigabyte

 

[Stayfr0sty]

I just got my first gigabyte board for my own personal rig and am very impressed with it.
Used to use Asus or DFI only.