I have a mid-2011 MacBook Air and 2 Dell monitors. A 30 inch (U3014) and a 27 inch (U2711).
I connect a mini DisplayPort to DisplayPort cable from the Air to the 30 inch monitor, and a DisplayPort to DisplayPort cable from the 30 inch to the 27 inch.
The 30 inch powers up as it should, but the 27 inch shows an error message saying that the refresh rate is wrong:
The current input timing is not supported by the monitor.
Please change your input timing to 2560x1440@60hz or any other monitor
listed timing as per the monitor specifications.
When I check the display settings in OS X, the 27 inch monitor doesn't even show up.
Is this a problem with the Air not being able to power up two displays that large?
Or is there anything I can tweak?
Someone told me the DisplayPort in the Air has a max supported resolution – I may have exceeded that.
Best Answer
MacBook Air cannot drive more than one external display.
I have Dell Ultrasharp U2713H and U2711 on my desk and I have tried daisy-chaining them with MacBook Air:
MB Air recognized only the first monitor in chain. Second display in chain mirrored the first one. Your error message is probably caused by signal cooked for U3014 (2560×1600) being fed to U2711 which cannot handle resolution higher than 2560×1440. Have you had lowered the resolution, you might have been able to see mirrored desktop on U2711.
At the moment I do not know (have not been able to find any information) whether macOS included drivers do support MST feature of DP at all.
There is an article About Thunderbolt ports and displays by Apple explaining how many of displays are supported with which Mac (though it does not explain why macOS does not support features (e.g. MST) with some configurations which Windows does support it (see Ed Andersen comment)).