14 DAY TRIAL // An Intel developer has submitted a patch for the X.Org server in order to enable 4K HDMI monitors, a feature that has been lacking.
AMD and NVIDIA already provide support for 4K resolution, but this patch should take care of any problems, although it's not yet available in the stable branch of X.Org.
“This series enables 4K HDMI monitors by making X not prune those modes. To do so, we parse the max TMDS frequency field in the HDMI CEA vendor data block and check the mode dot clock against it. Our QA tested it and the ChromeOS guys have merged it in their tree already and confirmed it does the trick for them,” said Intel developer Damien Lespiau.
X.Org 1.16 is expected to feature official hardware support for 4K HDMI monitors, but it's going to be a little while before it is available for download.