My late 2013 MacBook Pro is connected to an external monitor using a Mini DisplayPort to Dual link DVI adapter.
About once a day, the external monitor goes black. The applications continue running, and the MacBook's screen still works. The external monitor's light remains blue (yellow indicates that the source is unplugged).
The computer is sometimes cool to the touch when this happens, so it doesn't seem to relate to overheating. I'm not running any special applications. Sometimes it happens when I come back to my computer having not touched it for half an hour.
If I unplug and replug in the monitor, it works for a few seconds, and then goes black again. Same thing if I turn it off and then on again.
How can I figure out if it's a problem with my graphics card, my cable, or my monitor? I'd rather not replace something that's working.
