I also have exact same issue booting DX79TO with nvidia 770 (gainward, 2Gb). Rest of setup is as follows:
-DX79TO, latest bios 559
-i7-3820
-ram 32Gb -1333
-1ssd (sata2), 1hdd(sata2), 1hhd(sata3), all <1T and in ahci mode
-850w psu with 12V: 60+A and common
With old video card the system worked fine. With 770 it hangs at boot screen error 0_ and on board 00. And the 770 also works on other systems. Also the usb driver chooses by itself when it wants to have the keyboard available and when not. Half of times the keyboard doesnt work at post, e.g. cant enter bios with F2 and that sort of thing.
I am really, really disappointed with Intel this time, this board was high price but its very buggy and got a very bad experience with it. In retrospect i should of gone with other boards half price and no issues. If this is not solved soon, i will stay away from intel as possible - and also will advise like so. Atm my thumb is down for intel.
This *really* needs a fix from intel. Not from somebody else.