[noggin]

So on my kodi setting shall i change from hardware to software ? Or keep it as hardware ? What about amlogic 812 device if you compare it with chromebox i3 . And nvidia new box . 4k and 2k not important for now as i said cuz i dont hv 4k tv

If you select hardware and play content with a codec that your box can't decode in hardware, it will revert to software decoding. So you should be fine leaving your Intel NUC with hardware decoding enabled. Normally the default settings are good. There are exceptions to this rule, Intel boxes can't hardware decode 1080i VC-1 but can decode 1080p VC-1 - so you need to deselect VC-1 VAAPI if you have interlaced VC-1 content - usually TV series or concert Blu-rays.

If you have an i3 Chromebox and 4K isn't an issue for you, I doubt the Shield offers much to you. The Chromebox will do HD Audio bitstreaming and proper 23.976/24.000/50/59.94/60.00 frame rate switching, whereas the Shield doesn't bitstream HD Audio nor does it appear to do full refresh rate switching?

If your H265 content is within the CPU decode parameters of the i3 in the Chromebox you will be fine. (The Celeron Chromebox has more limitations in this regard than the i3 Model)