Computer doesn't recognize my monitor

[Gnaw Revilo]

Hey guys (btw first time post),
I've had a refurbished Dell T5500 for about 6 months with the following specifications:

• 
  2 Intel Zeon x5650
  12 GB memory
  Nvidia FX580
  1 TB hard drive
  windows 7 professional

Along with this desktop, I have also bought a monitor on sale at costco:

• 
  LG Ultrawide 25" monitor (model 25UM65-P)

I have connected the monitor to my desktop with a displayport cable. However, ever since I got my desktop and tried it, the screen would be black until the login screen would appear, which really bugged me since I could never access BIOS, but I thought nothing of it. Often I would wait 30 minutes for the login screen to appear at first. After the first 2 or 3 weeks, I only had to wait 3ish minutes.

However, now the waiting for the login screen has restarted. I have rechecked that my currently used and recommended resolution (2560x1080) is supported. I have no idea on why this happens. Could the problem be that the displayport cable is outdated (1.0-1.1)? Thanks.

 

[hang-the-9]

Try a different connection/cable/monitor.