I have an iMac Retina 4k, 21.5 inch, late 2015 All in One
OS High Sierra 10.13.2
I have 2 monitors. The secondary monitor is an ACER G235H 23-inch.
So! When the outfit wakes up from sleep the screens flash on for 1-2 seconds, off for 2-3 seconds (black screen) then back on normal; both monitors lit up. Whole thing takes maybe 5 seconds. During this scenario the main screen leads the secondary screen by ½ second.
Well this did not happen when running El Capitan. I did not run Sierra – went from El Capitan to High Sierra.
It does not happen with the secondary monitor disconnected. That is with the Thunderbolt wire removed from the iMac. Just turning off or unplugging the secondary monitor from the wall changes nothing.
What might be the reason for the flash and delay?
OS High Sierra 10.13.2
I have 2 monitors. The secondary monitor is an ACER G235H 23-inch.
So! When the outfit wakes up from sleep the screens flash on for 1-2 seconds, off for 2-3 seconds (black screen) then back on normal; both monitors lit up. Whole thing takes maybe 5 seconds. During this scenario the main screen leads the secondary screen by ½ second.
Well this did not happen when running El Capitan. I did not run Sierra – went from El Capitan to High Sierra.
It does not happen with the secondary monitor disconnected. That is with the Thunderbolt wire removed from the iMac. Just turning off or unplugging the secondary monitor from the wall changes nothing.
What might be the reason for the flash and delay?