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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.

2

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)).

0

The Current MacBook Air doesn't support two external monitors. According to Apple's MacBook Air Tech Specs page:

Dual display and video mirroring: Simultaneously supports full native resolution on the built-in display and up to 2560 by 1600 pixels on an external display, both at millions of colors

Generally, a machine can support one external display per Thunderbolt or HDMI port, so I don't believe that you can run both of your monitors without more hardware, which is supported by this answer on Apple's forums.

  • Daisy chaining should work. The MacBook Pro with Retina display is capable of running four external monitors. Two per thunderbolt port, daisy chained. But these displays might be too large for the Air. I'm sure it can run two 27 inch Apple Thunderbolt displays. – MartinHN Oct 16 '13 at 16:31
  • You are comparing a consumer machine with a software video card to a pro level machine with two video cards (one software and one hardware). Apples and oranges. The 2012 MacBook Air can daisy chain two thunderbolt monitors, but the 2011 can't. – Ɱark Ƭ Oct 16 '13 at 16:51
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    @MartinHN - OS X does not support daisy chaining via Display Port, even with "Display Port 1.2 compliant" Thunderbolt 2 ports. Windows 8.1 does support it on Macs with Thunderbolt 2 ports. See: discussions.apple.com/thread/4740489?start=30&tstart=0 – Ed Andersen Jun 24 '14 at 2:02
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i use a diamond USB adapter to work around that.. the refresh on both screens is a little slugish, but if you stay away from mission control and other graphic consuming resources, you should be able to get through the day with 2 monitors :) http://www.diamondmm.com/bvu195-diamond-external-video-display-adapter.html

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