Thanks for looking. This monitor no longer recognizes 2560x1440 as a native res. Most of the time I have to use 1080p. It flickers periodically. Getting it to recognize a signal and power on is sometimes difficult - have to shut everything down, unplug, then pray it comes back.
I can force it to 2560x1400 60 by using SwitchResX, an excellent Mac utility. However the text is fuzzy and the flicker is worse. Sometimes it will come back for a bit using the 2nd displayport output or HDMI on the Mac mini I have.
Connected to another display, the Mac mini works perfectly. The cable looks perfect, but I am trying to get another to eliminate that as a cause - note the HDMI has pretty much the same resume when I can get it to work. so likely it's not the cable.
The monitor is from 02/2013 and cost about $800. I expected to get more time out of it. I will reset it to factory and see what else I can do.
We never tested the seven year old U2711 on the Apple proprietary hardware and operating system.
Have you asked the Apple users here for their thoughts?
The U2711 HDMI in port was only validated to do 1920x1080p 60Hz. The U2711 DP in port is validated to do 2560x1440 60Hz. What specific mac mini (year) ? What video out ports are on the mac mini? What GPU/video is the mac mini using? What cables and convrters are you using to connect the mac mini to the U2711?