Problem:
New Dell U2715H monitor won't wake up from powersave mode after only one single successful connection with iMac 21.5-inch (2009) via the mini-displayport to displayport cable provided with U2715H, i.e:
mini-displayport out on iMac 21.5-inch --> mini-displayport to displayport cable --> displayport in on U2715H
I've tried several methods found on this and other forums, but they don't work:
1. disable the DDC/CI (i.e. menu > Other Settings > DDC/CI)
2. restart computer and monitor
3. shut down power for monitor forcefully
4. turn off the sleep mode in computer setting for both Mac OS and Windows OS
...
Strangely, the connection between U2715H and my Macbook Prof 15-inch Thunderbolt is fine, i.e. Thunderbolt out on Macbook Pro --> mini-displayport to displayport cable --> displaport in on U2715H, and each time the monitor can wake up from power save mode if the Macbook Pro wakes up from sleep, except that the audio of the Macbook Pro is gone when connected in this way which might be related to the use of mini-displayport end of the cable on the Thunderbolt port.
Anyway, I wan to ask if Dell's team can provide a solution on this eternal powersave mode issue? And advice from the community are also greatly appreciated!
Thank you!