Originally Posted by priuscat
My question is: since you need 120 hz to get the full effect of 3D with HDMI 2.0 is 4K 3D 60 hz per eye?
Yes, 120 screen refreshes per second, 60 refreshes per eye for L/R (aka 'SBS') 3D mode.
The incoming 3D L/R signal is 3840x2160 60Hz and is the same format as any 2D image at 4k/60. The TV's internal circuitry then un-interleaves the pixel columns 1,3,5,...3839 and displays them across the width of the screen for 120th of a second (one screen refresh cycle). Only the left eye sees this image. Repeat this for the right eye, except pixel columns 2,4,6...3840 are displayed.
So the incoming signal is 3840x2160/60Hz, and the TV converts this stream internally to 1920x2160/120Hz, then displays the image steam at 120Hz.