In my search for documentation about the NUC6I5SYH, I found this manual:
In the section "Installing and Removing Memory" the following is written :
"Intel NUC Kits 6I3SYH and 6I5SYH have two 204-pins DDR4 SODIMM sockets."
However, DDR4 SO-DIMM modules are 260 pins.
DDR3 has 204 pins. This should be fixed in the manual (And probably other documentation ?)
NUC Kits NUC6i3SYH and NUC6i5SYH have two 204-pin DDR4 SO-DIMM sockets