Well that's according to the raw specs but I could have sworn I read something on their web site that stated that only the gen 7 will fully support the 4k stuff. There is also an issue with the hdmi ports. If the chipset or the MB doesn't support HDMI 2.0, then it will also not be capable of full support, aka 4k at 60hz and full color. Otherwise you have to go to a add-on card solution of somewhere around the 1060 Nidia stuff. I don't like the add-on option for this as it is guaranteed to have several fans (which will eventually stop and overheat) and all the typical firmware/software bugs typical of those cards.
Nobody makes a low cost TV with display port yet.
Also, everybody assumes they are getting 4k when looking at a 4k tv but since they typically take the lower resolution inputs and synthesize the resolution to 4k, it looks a little better and therefore people assume that's what they are getting...maybe I don't need the higher res, but since the purpose here is to use it close up to program and stack as many screens in a possible, then I will assume I need it.