I don't know have somebody ever find this, but I've found a new and quick solution for loading backup bios :) I've tried a lot of solutions for loading backup bios over main bios, but none of them is a quick solution. Every solution was taken hours. But I've found a qucik way.
I must mod bios with gpxe, so I'm updating bios regularly. Sometimes, modding bios with gpxe is failed, so my machine doesn't start because of dead bios. So everytime I must recover bios with backup bios. But it is interesting thing that gigabyte's dual bios algortihm can't detect sometimes that main bios is started or not. So, we should disable the main bios awhile for loading the backup bios. I tried a lot of things, connecting VSS and HOLD# pins(previous post), shortening 5-6 pins, floppy, usb, etc.. I've been success with 5-6 pins method two times. But this method takes one hour or more, and it is some tiring. So I decided to examine the diagram of the flash spi chip that @Phaeilo gives the link (http://www.sst.com/dotAsset/40504
). After I examine it, I've realized that if I connect CE(Chip enable) and SCK(Clock), the main bios's CE cycle will be broken. If you look at the document you'll see that the chip starts working when the CE cycle goes to low from high state. If I connect to SCK with CE, then every cycle(beat) of the clock the CE's state change low to high then high to low, etc.. So backup bios can see that the main bios is not enable.
I'm not responsible if your mb is dead, I don't give any guaranty. if you want to fix your dead bios which has a backup bios and if the backup bios is not loading, then you can try this method. In Brief, you should have steady hands, a piece of wire(maybe paper clip). Power off the machine. Connect CE and SCK pins(1 and 6 pins). Then turn on the machine, but you should remove the wire after a second. I don't know excatly when you should remove the wire, but wou shouldn't wait long than 2 second. After that you should hear a beep sound. And you should see that backup bios wirtes on the main bios. Wait until the process is finished. After that the machine will restart.
My mb is Gigabyte GA-MA785GMT-UD2H(rev 1.0). A final notice is that don't touch VDD pin never(I was shocked :) ).