This is bizarre...
High-end desktop with Radeon 7870-based video card, was driving (5) U2713HM's just fine. I brought the system with me on summer vacation, but couldn't bring all the monitors, so just bought two new U3014's and shipped them to my holiday destination.
U3014's have been configured to select "Display Port" as input source. Using Dell-supplied cable, mini-DP outs on the video card are connected to DP-ins on the monitors. Monitors display "No DisplayPort Cable". Note that it doesn't say "no signal" - it says "No Displayport Cable". I've re-seated the DP cable a dozen times and re-checked the menu config is for DP at least that many times.
My first thought - maybe the video card was damaged in transit? Went out and bought a brand new Radeon HD7750-based card with BOTH dual-link DVI and mini-DP outs. The new card drives the monitors just fine in DVI (after re-configuring the monitors for DVI input, obviously). But it won't drive the monitors thru the mini-DP out!
My next thought was that something is wrong with the DisplayPort hardware in the monitors. So I tested it with my Precision M6700 laptop. The laptop has DP (not Mini-DP) out, so I had to turn the cable around. Reconfigured the monitor menu for mini-DP in, and it worked fine!
So now I've tried BOTH of these monitors with TWO different known-good video cards, and neither will recognize the DP input. Yet they seem to work fine on the Mini-DP input.
My next step will be to purchase Mini-DPxMini-DP cables and see if that gets them working with the desktop, but I'd still like to get to the bottom of why they're not recognizing the regular DP input. Is there a known bug here?
Thanks in advance!
ET