I had the sleep issue with my SuperMicro X10SAT, which has DisplayPort 1.2 on it. The monitor would sleep properly if the computer itself went to sleep, but before that, when the screen was not in use, it would cycle the "entering power saving mode" message endlessly.
My bigger issue was that when the monitor came back after being inactive, the windows were resized and repositioned. That was unacceptable. I returned the monitor (which I did not get from Massdrop - fortunately). That was too bad. I really wanted to like this monitor - and I got a good one.
I was using Windows 8.1.
I posted more about my experience back on page 46 or 47.
My bigger issue was that when the monitor came back after being inactive, the windows were resized and repositioned. That was unacceptable. I returned the monitor (which I did not get from Massdrop - fortunately). That was too bad. I really wanted to like this monitor - and I got a good one.
I was using Windows 8.1.
I posted more about my experience back on page 46 or 47.