From what I've read I don't think it's possible to get 120 Hz @ 4k due to bandwidth limitation with HDMI 1.4. I read that with certain monitors and recent NVIDIA drivers you can run the monitor in Y:U:V 4:2:0 mode to reduce the bandwidth and then get 60 Hz but the color quality would be poorer (assuming it even works). All the things you propose would be very interesting, but I don't have the time or expertise right now to do this. I got one of these monitors that was shutting down randomly and this work was primarily motivated by debugging what was wrong hoping I could fix it. I ended up sending it back before I started this work hacking the firmware.