DisplayPort definitely supports it, and I'm pretty sure Intel HD4000 supports it. Not sure about OS X, though, as I've only bothered with it on a gaming (Windows) machine.
Worst case scenario is you'd be running the monitor at 60 Hz.
My 144 Hz monitor automatically goes to 60 Hz when I plug in a single-link DVI connector.
Can you create a custom 1920x1080 120 Hz resolution in SwitchResX and see if you can make the monitor work in OS X at full refresh rate?
What about 105, 110 or 115 Hz?
HDMI should support over 60 Hz, but the monitor may be configured to only report 60 Hz as a supported refresh rate. Try creating a custom resolution in SwitchResX at a higher refresh rate and see if it works.
I was able to run my Seiki 4K TV at 1080p 110 Hz over HDMI from 2012 15" rMBP.
What's the highest refresh rate that works? Have you tried 105, 110, 115 Hz?I created a custom resolution which I think is correct (I saved then copied my EDID info for 120hz)in SwitchResX.
Unfortunately after a reboot the custom resolution shows as invalid.
Still 100hz is better than 60hz
I have to purchase SwitchResX to allow more than one custom resolution. It wont let me delete the 120mhz custom now from the menu.What's the highest refresh rate that works? Have you tried 105, 110, 115 Hz?