Using 4K displays and Ultra HD TVs with Mac computers
"You can use 4K displays and Ultra HD TVs with these Mac computers.
MacBook Pro (Retina, Late 2013 and later)
Mac Pro (Late 2013)
iMac (27-inch, Late 2013 and later)
Mac mini (Late 2014)
You can use 4K displays and Ultra HD TVs at the following resolutions and refresh rates via the built-in HDMI port.
3840 x 2160 at 30 Hz refresh rate
4096 x 2160 at 24 Hz refresh rate (mirroring is not supported at this resolution)
With OS X Mavericks v10.9.3 or later, the following DisplayPort displays are supported at their default using single-stream transport (SST) at 30Hz.