Hi. Set aside about an hour to do this.
If you have Windows ?? (7,8,8.1) and a SSD drives installed then getting Windows 10 on USB from NewEgg, Amazon, BestBuy, etc is easy (No product/seller endorsement / recommendation implied)
Create a boot USB and backup your system to an external drive.
Then shut down the NUC, boot from your recovery USB and "restore" your system to test it. If this sounds scary (I've seen VPs go pale when I suggest this) its ok. Backups are ok. Its restores that count. Trust me. People agree to doing "backups" Restoring a dead system, particularly a production system, has gotten me awards and food.
Once you can restore your system, take the Win. 10 USB out of the little box it comes in and proceed.
I'm not suggesting you make a backup copy of Windows install USB to another 16Gb USB, but do you really want to have to buy another?
After backing up the Windows 10 install USB (that i did not suggest to do, and will say so in court put the original MS Win install USB back in the box. Never share software.
Shutdown and turn off your NUC, Insert the install USB, and Turn on the NUC.
Follow the steps. The only option I remember is selecting "Upgrade the currently installed version of Windows"
The rest was easy.
If you are starting with "bare metal", "virgin system", "cold iron" or "blank slate" with new SSD drives then follow this.
Booting This aplies to Its very easy. I'm still having some issues with UEFI but Legacy boot works.
NOTE: I suggest using a wired keyboard to make BIOS changes and do a fresh install. Just to keep it simple. Also having a hard wired modem connection to the cable / DSL / V.56 or acoustic modem.
1) Pick your SSD. I've used Samsung and non Samsung 512 Gb PCIe that are ACHI (older) and newer faster NVMe. Both ACHI work under Legacy.
All were ordered off of Amazon (No endorsement implied. NewEgg, etc are also good )
2) Windows 10 and Windows 10 Pro come on USB drive. I used the front blue USB port. Not that I'm suggesting backing up the USB and use that one.
3) Get a small, very small screw driver to open up the bottom of the NUC (Personal gripe) I wish a small screw driver had been included with the NUC, along with the Allen wrench.
4) Does not matter which slot the PCIe SSD goes in. Yes they are smaller than the memory stick. Kind of freaky.
5) If you have changed your BIOS boot to UEFI, try Legacy first. Both work but I had some issues with Networking. This sounds like an issue on my end, but to make sure its all good do a dry run first.
6) Start the NUC, possibly with the backup USB in the blue port.
7) Get out the little card with the key symbol on it. You will need the number on the back. Walk through the install. Do not select "Upgrade a current version"
8) It really was simple.
9) Windows 10 - oy vey! The "Settings" menu item is your friend. You can set up WiFi and down load the windows patches. I have not found a way to put windows patches on a USB yet.
Hope this helps.
I suggest you to follow the procedure from the following link:
Windows 10 Forums with some exceptions:
1. Since you have your Windows media on DVD and you have DVD drive I believe that you can use it for installation instead to create USB with the Media Creation Tool.
It will take more time to install the system then when using USB media.
2. Connect your DVD to the NUC and switch it ON. Insert your Windows 10 installation disk into DVD drive. Switch the NUC to OFF.
3. Switch the NUC to ON and when INTEL logo appears, depress F10. Boot menu will be displayed. Chose your DVD to boot.
4. Execute paragraphs 5 trough 10 in the above Windows 10 Forums procedure.
5. Continue from paragraph 13 (UEFI) trough paragraph 16. In paragraph 16 click on Customize.
6. In paragraphs 17, 18 and 19 set all options to OFF.
8. Execute paragraph 20 and 21. I thing that in beginning you shall sign to you local account. So continue from paragraph 24. You will be able to sign into Microsoft Account later, after Windows is installed.
9. Execute paragraphs 24 trough 28.
10. After Windows is installed, download and install all NUC6i5SYH drivers from Intel Download Center: