Please check the information on post #3 at this thread https://communities.intel.com/message/247428#247428
An update: Here are the instructions for OpenELEC specific installations on this NUC. These steps were reported by a user who used the development build at http://snapshots.openelec.tv/OpenELEC-Generic.x...-r17148-gb48ea69.tar. We are in the process of validating these steps, but I wanted to pass this along to you now.
Press F2 when prompted during boot to enter BIOS Setup.
Press F9 to set all BIOS options to default values.
On the Devices and Peripherals > USB menu:
Set USB3.0 (XHCI mode) support to Enable
Check USB Legacy to enable it
On the Devices and Peripherals > SATA menu, set Chipset SATA Mode to AHCI.
On the Devices and Peripherals > Video menu, set the IGD Minimum Memory to 512 MB.
On the Boot > Boot Priority menu:
Uncheck UEFI Boot to disable it
Check Legacy Boot to enable it
On the Boot > Boot Configuration menu:
Check USB under Boot Devices to enable it
Press F10 to save your changes and exit BIOS Setup.
Proceed with the installation of the operating system.