I had pretty much the same problem as you just last night.
First off, I must say that all my components were newish but well tested in the past couple of weeks.
For a reason, I won't go into right now, I did a complete tear down of my case and rebuild.
I went into BIOS to reset a ran curve then could not get a Display port signal.
I tested all the parts separately on another system an all was well with each.
Looking back, In the rebuild I had a hard time screwing the Video PCI bracket down. The hole just would not line up.
They were a half a hole short. I looked toward the back of my Graphics card (the end opposite the DP connectors)
A bunch of cables were kind of back there. I'm now thinking that one of the small cables got back there and interfered
with the setting of my card. I notice you have an ITX case also. Try resetting the card paying close attention to
not having any cable get in way of the back or underneath. When I did this, I didn't have any trouble with the holes matching up, nor any trouble with Display port signal. Good Luck.
