Apple's early 2015 MacBook Air confirmed to support 60Hz 4K external displays
While Apple says that its latest MacBook Air will officially support external monitors with resolutions up to 2,560-pixels-by-1,600-pixels, tests have shown that the slim portable can actually drive an external 4K display at a full 60Hz.

Testing the early 2015 MacBook Air with a Dell P2415Q 24-inch 4K display yielded positive results, according to Ars Technica. The Air correctly identified the attached monitor at 4K resolution, switching the user interface into HiDPI mode.
Subsequent refresh rate tests confirmed that it was running at 60Hz, and the publication said that interface components were "more than smooth enough for desktop use." Problems cropped up when performing animation-intensive actions, like entering full-screen mode, with "clearly visible" frame lag, showing that the display pushes the Intel HD 6000 graphics chip near its limit.
That limit is exceeded when using OS X's built-in resolution scaling functions, with the integrated GPU turning animations into "flip books" when asked to render higher resolutions. Even scrolling performance is said to suffer in that situation.
While the MacBook Air's Tech Specs page does not list 4K compatibility, the early 2015 Air is listed on Apple's 4K display support document. There, however, it is only shown with the capability to push 30Hz or 24Hz, rather than the 60Hz Ars discovered was possible.
This is not out of line with Apple's specification history, as the company often lowers the "official" capabilities of its products below what they are theoretically capable of. Many of the early unibody MacBook Pro generations were listed with maximum RAM capacities of just 8 gigabytes, for instance, despite easily supporting 16 gigabytes.

Testing the early 2015 MacBook Air with a Dell P2415Q 24-inch 4K display yielded positive results, according to Ars Technica. The Air correctly identified the attached monitor at 4K resolution, switching the user interface into HiDPI mode.
Subsequent refresh rate tests confirmed that it was running at 60Hz, and the publication said that interface components were "more than smooth enough for desktop use." Problems cropped up when performing animation-intensive actions, like entering full-screen mode, with "clearly visible" frame lag, showing that the display pushes the Intel HD 6000 graphics chip near its limit.
That limit is exceeded when using OS X's built-in resolution scaling functions, with the integrated GPU turning animations into "flip books" when asked to render higher resolutions. Even scrolling performance is said to suffer in that situation.
While the MacBook Air's Tech Specs page does not list 4K compatibility, the early 2015 Air is listed on Apple's 4K display support document. There, however, it is only shown with the capability to push 30Hz or 24Hz, rather than the 60Hz Ars discovered was possible.
This is not out of line with Apple's specification history, as the company often lowers the "official" capabilities of its products below what they are theoretically capable of. Many of the early unibody MacBook Pro generations were listed with maximum RAM capacities of just 8 gigabytes, for instance, despite easily supporting 16 gigabytes.
Comments
Another example of the slow, tortured rollout of 4K UHD.
To someone who doesn’t understand business maybe but just snappong one’s finger and a new format takes over is not how it works.
Another example of the slow, tortured rollout of 4K UHD.
Drop the last letters. Using three and four letter combos as resolution names is horrendously stupid.
On a side note, a certain scumbag company is now selling SUHD tv's.
Under promise, over deliver. A good philosophy.
I try to do this and sometimes it makes people uncomfortable. I don't like to oversell it. I can come off as pushy when I'm doing that. I'd rather people just come to it themselves after I put it out there.
Can the new MacBook support these displays as well?
MacPlug Pray%u2122 ?
So when people complain, Apple can just say, "we never claimed it would do 60Hz 4K"
Would you do any different? You know some attorney is getting ready to file a class action over anything Apple does.
I do think this is better than them blocking 4K 60 altogether when it can meet some use cases.
Too bad it may not work with yesterday's printer...
So when people complain, Apple can just say, "we never claimed it would do 60Hz 4K"
When you read the details about how animations become flip books at that resolution, it really can't (and Apple is justified in not claiming it can). Even though the Intel GPU used in the Air can output a signal at 60Hz 4K, it's clear that it simply doesn't have enough power to do anything more than display static images.
I've worked on optimizing software for 4K displays, and it's amazing how many people will buy a 4K display, turn around and try to run it with something like an Intel NUC, and then complain to customer support when everything is laggy. When you spend far more on the display itself than the computer used to run it, you know there are going to be problems. You get what you pay for.
Super Ultra High Definition?
Is that like Super Duper AMOLED?
I think it's the difference between Apple and other companies. Apple doesn't score a "features list checkbox victory" by claiming a feature unless it works well. Whereas the Samsungs and the LGs of the world would tout that same half-assed feature in their advertising.
In any case, Apple's not "blocking" 60Hz 4K, just not saying it's officially supported.
I am more interested in seeing if those Macs on the list support DisplayPort MST for multiple standard resolution monitors instead of just a single 4K monitor. Has anyone with a Thunderbolt 2 Mac tried using a DisplayPort MST hub, or tried daisy chaining DisplayPort 1.2 monitors to see if it works on the Mac?
To someone who doesn't understand bespoke consumer products that excuse might fly, but forcing consumers to cobble together a 4K solution as a DIY electronics experiment amidst a compatibility minefield is not how it should work.
This sounds good.
Can the new MacBook support these displays as well?
Go get one and report back to us.
Thanks for the helpful reply.
I will resist putting a hex on you.
I am more interested in seeing if those Macs on the list support DisplayPort MST for multiple standard resolution monitors instead of just a single 4K monitor. Has anyone with a Thunderbolt 2 Mac tried using a DisplayPort MST hub, or tried daisy chaining DisplayPort 1.2 monitors to see if it works on the Mac?
If it can do 4k @ 60 Hz then it ought to be able to use MST for multiple lower res monitors. It isn't displaying 60 Hz 4K without using MST.
If it can do 4k @ 60 Hz then it ought to be able to use MST for multiple lower res monitors. It isn't displaying 60 Hz 4K without using MST.
The tone of some of these postings implies that unless Apple officially states that something is supported, people should not expect it to work properly, no matter how obvious it may seem. Since Apple does not officially list MST hubs or daisy chaining DisplayPort 1.2 monitors as supported, I am hesitant to go out and buy these things only to find out they do not work properly. And if people point out that the DisplayPort MST should obviously support multiple lower res monitors on the Mac, they might be accused of "features list checkbox victory".
The tone of some of these postings implies that unless Apple officially states that something is supported, people should not expect it to work properly, no matter how obvious it may seem.
Apple is unlike most other companies in the industry in that they will not claim official support for something unless it works _well_. So even though the latest MBA can support 4K @ 60Hz simply because the Intel HD 6000 GPU inside supports it, the performance sounds pretty horrendous when you actually try to use it.
In my experience, Intel's GPUs are pretty much minimum spec for running 4K. If you're watching videos, they should be fine. But if you're using applications that require interactive graphics (e.g. Keynote, iPhoto, etc), they'll be anywhere from sluggish to unusable.
Same holds true for MST -- the higher the resolution and refresh rate of the monitors you have connected, the more you're pushing the GPU, and thus the slower it'll get in many situations.