I recently purchased a 2011 Intel Imac running Mountain Lion. I hooked up an Acer H243H monitor to it using a thunderbolt to HDMI converter. I also have a separate Windows machine plugged into the Acer's DVI port. The only empty port right now on the Acer is VGA.
The problem is that I need to have just my HDMI port plugged into the Acer in order for my Mac display to show, and then I can plug in my DVI for my Windows display. What is happening is that whenever I switch to the DVI input and then go back to HDMI, the monitor "times out", or gives up trying to search for a signal, and then switches to VGA (and gives up) before switching back to DVI. While searching for a signal on each port, the Mac screen flashes to a solid aqua-blue color, and then returns back to its normal display as my Acer cycles and times out before settling back on DVI.
So, my gut tells me that the Acer monitor needs to wait a little bit longer in order to have the Mac send over its display data, but I am stumped at this point. I have consulted the H243H manual, and none of the options seem to work. It would be nice if the monitor could just stay on any input I choose, but unfortunately it cycles through automatically, looking for data. The only solution I have is to unplug the DVI, coercing the monitor to freak out and look for a display that has data no matter how much time it may take.
So my question is: is this a Mac issue or an Acer issue? Is there a way to disable auto scrolling through displays on the Acer monitor, or is there a keyboard command I can press while the Mac screen is solid blue to facilitate the display rendering on the Acer?