I use NUC8i7BEH and UHD dual monitor(same model).
first monitor is connect ctype to hdmi, second monitor is hdmi to hdmi. problem is occurs in second monitor(hdmi). I tested monitor change case. too.
I use 1~2 movie and webpage, filemanger.
hdmi monitor show below symptoms.
first I know it is monitor problem, I change by same other monitor.
but It show same issue, and It only occurs connected by hdmi.
It seems that noise is generated when you use a lot of memory.
Current bios version is 66. It only can setup graphic memory max. 1G.
but current website's latest version is 51. last version 2 is removed. and I can't downgrade to 51. it failed.
Please check to support UHD dual monitor.