so I managed to get a moment to test using DP (using the cable included with the monitor) and I get the exact same audio issue... pretty sure its safe to say its faulty at this point?
WARNING - might be loud when the game audio kicks in...
launching Pumpkin Jack is a really quick way for me to duplicate the issue for some reason, but it will eventually start making a quieter noise just sitting on the desktop too...
What volume level do you have the FV set at? Looks like it unless both cable is being route through something that generate a lot of EM noise.