As fair as i know ExtendedBootBlock (that is missing in bios) is in case flash recovery (sometimes you can flash your mobo powering it up with USB key with FORMULA.ROM file on it, if main bios checksum is incorrect). So in case that everything works, it should never be needed.There is always a way to force flash certain bios on mobo there is AFUDOS ES (Engineering Sample), that allows you to flash any bios to any Asus mobo with AMI bios without ANY checks... recepie for disaster unless you can flash mobo over SPI interface. SPI interface allows you to flash mobo from other computer using LPT/USB interface, making LPT/SPI cable is also easy enough, even tho i didnt try it yet. But if someone is interested in "EXTREME" bios recovery check it here. When i flashed "broken" (read to much customized) bios, i RMAed mobo, before i found out this article, or i would try this method back then