Here is a summary of my reasearch concerning problems under Maverics with setting proper resolution for 2560x1440 monitors when they are rotated to the PORTRAIT position (pivot 90 deg).
My MacBookAir 4,2 (13'' mid-2011), after updating to Maverics in December 2013, stopped to work properly with my two external 2560x1440px monitors:
– Dell U2713HM
– HP ZR2740w
when they are rotated into Portrait position. In Lanscape it works fine. In Portrait it cannot set right resolution.
Apple support, after 3,5 months of contacts, is still unable to help or even diagnose what is wrong. Update to Maverics 10.9.,2 did not help, of course. (The most fanny advice I got so far was to contact monitor manufacturer for a monitor firmware update).
Additional info that may be relevant:
In all my test described below I use the same miniDisplayPort-to-diplsayPort cable.
At the moment when I updated from Lion 10.7.5 (under which my monitors worked fine in Portrait) to Maverics, one more update was installed. It was Thunderbolt 1.1 update. So I cannot say, whether responsibility goes to Maverics or to Thuderbolt update.
My research:
So far I have tested with OS X 10.9.2 (SUCCESS – getting 1440x2560px in rotated mode; FAILURE - getting only lower resolutions):
– 3 MacBookAIr4,2 (13'' mid-2011) – FAILURE (all 3)
– 1 MacBookAir6,2 (13'' mid-2013) – SUCCESS
– 1 MacBookAir6,1 (13'' mid-2013) – SUCCESS
– 1 MacBookPro8,1 (13'' early-2011 or late-2011) - FAILURE
– 1 MacBookPro8,2 (15'' early-2011 or late-2011) - SUCCESS.
I also booted OS X 10.9.2 from an external disk connected (with the same cable and monitor):
– to my MacBookAir – FAILURE
and then
– to MacMini - SUCCESS.
It is apparent that the models which have problems with finding proper resolution in Portrait position are older models with older graphics cards and possibly some other older hardware. The most striking is that they worked okay before updating to Mavericks (well, to be honest, with OS X 10.7.5 I tested only my MacBookAir and it worked fine in Portrait for 1,5 year).
My questions:
1. Could the Thunderbolt update be the source of problems? Could it be undone?
2. Is it possible to use some drivers from 10.7.5 or 10.8.5 to get right resolution in 10.9.2?