Looking more in to the problem, its seems i cant change command rate its always at 1T (SPD profile has it listed at 2T), maybe that's why the system won't boot with 2 sticks?
I am sorry to hear that have had issues with your NUC computer.
At this stage, Intel does not release beta BIOS for Intel boards.
You will need to check downloadcenter.intel.com for driver releases.
If you need information about fixes and known issues. they will be available on the BIOS releases
Is there a plan to release a BIOS which will support dual 1866Mhz mode? Because i can't understand how can the NUC work with no problem with single stick of RAM, but cant boot if i insert both.
Also there is a problem with command rate settings, no matter what BIOS setting i use (2T or 3T), bios uses 1T. (Checked with several programs in windows 8.1)
I am also curious what setting does the bios use when the NUC is first started, does it read bios values ( if bios setting in configured to manual, lets say 1333 or 1600Mhz mode), or does it read SPD of the ram stick?
Please bear in mind this motherboard model does not support 1866 MHz memory. So, Intel will not release BIOS updates that support your memory. Your board can handle DDR3L 1333/1600, 1.35V
The motherboard reads BIOS configuration and takes lower memory speed supported to boot, in this case, 1333 MHz.
I've got the same problem:
Crucial Ballistix 16 GB RAM Kit 1866Mhz @ 1.35v not working with NUC 54250WYK.
How frustrating it was to be greeted by NUC's first boot with the infamous '3 blinks of death' !
The kick in the teeth was allan_intel's answer in this thread, now I feel pretty bad about my purchased knowing that the only 'fix' would be using a single stick on the slot farthest from the CPU or having to beg customer's service to exchange my Crucial Ballistix 16 GB RAM Kit 1866Mhz @ 1.35v by a DDR3L 1333/1600 kit
Sour taste in mouth.
Just a quick follow-up on this... after checking with the engineering team, it appears that an entire hardware change would be needed to make dual-channel 1866 MHz work - definitely more than just a BIOS update unfortunately.
At this time, there are no plans to add 1866 MHz memory support.
I am not from Intel but I think there may still be confusion when tossing around terms like "1866" and "support." Of course full "support" may imply operation at maximum speed and being able to get help. Instead, I suspect many people like myself are just trying to understand why some memory which has 1.35v 1600 settings standard (plus more) doesn't operate except in single slot furthest from processor. It is sort of like saying why not allow an H or V speed rated tire instead of just S rated. It may be harder to find the slower rating for sale.
Having said all that, I am thinking the problem may be the "density" of older memory being less than 4Gbit and/or the 2T that someone mentioned. Searching the web for NUC 1866 shows some failing but some working.