I recommend the following steps.
1.Reformat USB thumb drive with FAT32 ( not the quick format, uncheck this option). often the thnumb drive is the problem so if after reformatting this procedutre does not work i highly suggest trying some different thumb drives.
2. Download the file from the above link. This was most recent BIOS as of this post (10/28/13). check ASUS website for most current BIOS. this is BIOS #1301
3. With power disconnected, plug the PSU into the motherboard's 24 pin power connector. Leave any other power connectors unplugged including the CPU 8 pin power connector
4 Turn the PSU on and then the MOBO should light up. Do NOT power on the MOBO just leave it lit once the PSU is turned on.
5. Insert the USB thumb drive with the above file in it's root directory into the white USB 2.0 on back of MOBO (at the bottom of the USB stack next to the BIOS button)
6 Hold down the BIOS button for 4 seconds. It should flash once then pause and then begin flashing steady as it updates the BIOS. Takes a few minutes. If the light goes solid after a few seconds the BIOS update did not work. If it flashes beyond 5 seconds that should indicate the process is going and you should be good to go.