| 4K on Mac
Currently, official support for 4K resolutions on Macs is sparse: Apple states the only two models to support it are the new Mac Pro and 15-inch Retina MacBook Pro (Late 2013 and newer). That’s partly because these are the only Macs to support DisplayPort 1.2, which is the protocol needed to support 3840×2160 at a refresh rate of 60Hz. Even these Macs don’t support 3840×2160 at 60Hz over HDMI, though – you’re limited to 30Hz, meaning animations and movement in OS X appear less smooth. In all cases, you have to specifically enable DisplayPort 1.2 support on the monitors. However, despite its official support, we did have a problem with the Mac Pro running at 60Hz over DisplayPort 1.2 – it has some sort of driver error with its graphics cards that caused display errors on the right edge of every display except the Dell. It was fine at 30Hz, and the Retina MacBook Pro was fine at 60Hz. Hopefully, this will be addressed soon.
However, don’t abandon hope for 4K if you don’t have a 15-inch MacBook Pro or new Mac Pro. You won’t be able to get 60Hz on other machines, but we tried other Macs with the displays, and many were capable of supporting the resolution at 30Hz, including the latest 13-inch Retina MacBook Pros. It’s not just newer Macs – the oldest we tried successfully was a Late 2008 15-inch MacBook Pro. However, older Macs and newer ones with lowperformance GPUs (including a Late 2012 MacBook Air) did suffer from a few display glitches when connected, which could affect usability.
One thing you’re likely to find if connecting one of the unofficially supported Macs to a 4K screen is that pixel-doubled ‘Retina’ mode may not kick in, as it does with the supported models, meaning that OS X’s interface will be tiny. You can manually activate a Retina mode to 4K screens, though, so the interface appears at 1080p size (but with double the detail).