Why don't you think the video card is the problem? What version of the BIOS are you using?
I would put your old video card in and try to install Windows again. You should not be seeing A2 or any code when at the desktop. Are you sure you have the OS drive connected to an Intel SATA port, and not the ASMedia SATA ports? You would need to load a driver during the installation if using the ASMedia SATA ports, which is not worth it since the Intel SATA ports are far superior. I'm not even sure if the Windows 7 msahci driver will work on X79 chipsets, did you install a driver when you first installed Windows?
Actually, what version of Windows are you using?