You say the BIOS file from Asus is too large for your lappy's BIOS chip, that doesn't sound right to me.
I'd first get into some details about what you have and do the same at the Asus site. I'd be willing to bet you'll find something if you dig deep and long enough.
May even want to shoot Asus support a message and just ask about it to see if the difference in BIOS size with the model you have is a known issue or if they could shed some light on that for you.
Be sure to know how large the BIOS file is vs how large the util says your BIOS chip is itself and so on.
