I received my RAM kit today and threw it in the NUC. I blew the NUC out and cleaned it a bit although it seemed fairly clean from what I could tell. I was unable to adjust any of the RAM multipliers or timings in the BIOS and therefore it is running at 2400 MHz. I did notice there is one BIOS revision from June this year which is newer than what I'm running, so I will flash that tomorrow. I doubt it changes anything pertaining to RAM speed.
Quick observations after rebooted with 32GB RAM. I still see minor flicker which is a bit annoying. I have not noticed the black screen so far.
Unfortunately there is very little I can do to make this NUC process video any better as far as I can tell. I suppose I'll test this memory for a few days and likely return it to Amazon. I think the resolution I'm pushing on this 38" monitor, even at 60 Hz is just a little much for the NUC. So what I may do is just switch back to my 32" monitor as there was no problem before when using that display.
Thanks to everyone for suggestions / advice and do have a great weekend.