You will need HDMI 2.0 for that.
HDMI 1.4 and 2.0 are identical in hardware spec. It´s only a matter of updating the code to enable 2.0 on nMP & rMBP. Why not do so with 10.9.3 which focuses on improved 4k support? Anyway, if someone can check let us know. A lot of people are curious.