We seem to have the same motherboard. I am running the AHCI mode without problems. Have you tried removing the Graphics and just using the onboard graphics?

Are you booting UEFI? If you are, there is a later bios update (1406) that refers to hangs when running a GTX 680. Maybe it could effect yours also.

We also had someone the other day that had graphics problems when he used the AHCI controller. It was a Gigabyte Z79 type board, but close.

But asking ASUS and perhaps getting a board replacement might be the best option. I have had mine for about 2 weeks.