Whenever the Windows 7 power management "turns the display off", the monitor enters into power saving mode. However, it gets stuck in a loop, alternately turning the back light off, then displaying "entering power save mode". The monitor power LED stays blue the whole time, and any presses to the monitor buttons displays a message about no input signal.<<< LOOP
I have a desktop using 2 dell DELL P2411H they are using 2 Mini Display Port 1.2 It will go into power save mode then come out of power save mode and go back into it. Its just a 5 second loop so it never goes into sleep mode. I also have 2 dell Dell P2211H Black 21.5" 5ms they don't go into this loop thing of power save mode. They work just fine. I also replace the video card.
Windows 7 Ultimate
AMD ATI 7990 Graphics card
AMD ATI 4890 Grahics card <<<< used for testing
2 Dell P2211H Black 21.5" 5ms