Sharing monitors between computers
I have two computers and two monitors – a Mac Pro with a 27-inch Dell monitor connected using DisplayPort, and a Windows 8 PC with a monitor (also a Dell), that’s shared between both the PC and the Mac Pro (over DVI on the PC). If I’m using the PC and then unplug the monitor and connect it to the Mac Pro, the Mac recognises the new display, but the screen stays black. After a few seconds the monitor goes into standby. Is there any way to hot-swap these monitors? Steve Byron OS X sends a query to the monitor through the video cable when the Mac first boots or wakes from sleep, when you plug in the Mac end of the video cable, and when you hold å down in Display Preferences and click the Detect Displays button.
If the monitor doesn’t answer with its display ID at any of these points, the Mac will conclude that there isn’t anything at the other end of the cable and will stop sending video data through it. And the monitor in turn, will drop to standby as soon as it goes a few seconds without receiving a video signal.
It may be that your monitor isn’t responding because it’s only listening to the PC through the DVI port at the time and doesn’t switch over immediately. You could try using the Detect Displays button on the Mac to send a few extra ID queries down the cable and see if the monitor catches any of them. If that doesn’t work, try cycling the power on the monitor first, before you plug it into the Mac. Even if this works, it’s a little inconvenient to have to turn the monitor off and on again every time you switch computers.
However there is a glimmer of hope. There are a few monitor detection bugs in Mavericks 10.9.4 that Apple is aware of. By the time you read this, 10.9.5 will be out, not to mention the possibility of 10.10, Yosemite. There is a good chance that Apple may have fixed this issue in the display driver by then, allowing better hot swapping detection.