I am not sure what happened. Installed the memory and 3 blinking lights occurred on power button indicating memory failure.
Opened up the NUC and looked at the memory.
Pretty confused as this meets ALL requirements of the NUC.
Returning for replacement.
The NUC better not have issues. Very disappointed so far.
I did try the second , non-failed memory stick in both slots, without issues, and the NUC booted.
The one that had the problem was in the slot closest to the mainboard. it says DIMM1 , but silkscreening is kind of confusing.
If the second stick worked in both slots, then you have one bad stick. Return the pair to neweg for replacement.
Doc (not an Intel employee or contractor)
[Windows 11 is the new Vista]
Update - Nov-4-2021 :
Received new replacement memory. Identical to first set.
Tested each stick individually, in each slot separately with MemTest86, single pass only.
No failures on any test.
Installed both stick simultaneously.
Ran same single pass test with both sticks installed with zero (0) failures.
All good in the land of Phantom Canyon NUC with Gskill 64gb kit.