Ok, I've come across a very bizzare issue, I have no idea whats going on.
Got a replacement displayport cable today, and discovered that the new cable will only work on displayports 2 and 4 on the card.
The old cheap cable works on all 4 displayports....
If I connect the new cable to ports 1 or 3, then I get a constant "connected" and "disconnected" sound playing. Like it will connect, then immediately disconnect, and repeat that until I unplug it. No display at all and no dialog on the screen. Just blank.
Very bizzare, because the cheap cable works on all ports....
Once I connect the new cable to a working port, I have this message on the screen:
The system has detected a link failure and cannot set the requested
resolution and refresh rate of your Displayport display. Your display
might not support the requested resolution or there may be an issue
with the cable connecting the display to your computer.
Im stumped... Card is obviously not faulty because the cheap cable works fine on all ports, but the new cable cant be faulty either because it works fine in ports 2 and 4.... wtf?
The cable is a Monster Digital Life Displayport Cable
Looks like this: