Hi.
Mine was running fine with a GTX 760 and an N300 until last night. Suddenly the motherboard beeps that it cannot find a video card and I can't display the bios unless I remove the GTX 760. Everything in the BIOS seems fine. I have 043 I believe. I have reseated the video cards but it still will not display the bios. I can Remote Desktop to the machine in Server 2012 and then it shows both cards, but only after I reinstalled the windows drivers for the GTX 760.
When I bought the MB, it had to be replaced as it could not upgrade the bios from 039 to 040. When that was fixed, I had a really hard time getting the GTX 760 to work with the N300 (I need the N300 to handle video, as I use the GTX 760 for CUDA computation).
All in all, probably my last Intel MB. I have built countless numbers of machines since the 1980s and this MB is definitely the most pain I've had.