And just to backup the info Dougho kindly has described and for future reference of NUC users, I am pasting a page of the NUC D54250WYKH Technical Specifications ( http://downloadmirror.intel.com/23089/eng/D54250WYB_D34010WYB_TechProdSpec06.pdf ) .
For 8GB modules the chip density required is 4Gbit, i.e. 8 chips in one side of a double sided SO-DIMM, and the speed must be 1333/1600Mhz. Pretty tight requirements, but it is what it is. Sometimes painful for people having to buy memory again. (This info was already provided by dougho in one of the links of his previous post).
Regards,
Victor
P.S. The part I am disappointed, is that no Intel person showed up in this thread.