I have 1920x1440 in a 19" screen.
Sounds lovely - is it a CRT? If not what's it called? (A few years back you could get 1600x1200 LCDs but everything has become letterbox since then.)
Also, you should know that your claims about driving 3840x2160 are a bit misleading. You may be able to do it over a single HDMI link, but you're not getting full 60 Hz progressive refresh. HDMI doesn't have enough bandwidth to support that. You're probably dropping down to ~30 or even ~15 Hz refresh.
That's what I suspected too. Usually there is an on-screen display which shows you the refresh rate you're using.
An authority is a person who can tell you more about something than you really care to know.