I managed it with Win 7 pro 32 bit.
The first time I used the Intel USB 3 creator utility, but it stalled at that point.
When I did it manually with the 32 bit version it only worked if I injected the x86 (32 bit) drivers not both 32 and 64 bit drivers.
I cant remember the exact sequence but I do remember swapping keyboards at that point.
I could not get it to run 16 bit programs. NTVDM just would not work, so I upgraded to WIN 10 32 bit, but again I could not get 16 bit programs to run properly, also it only used 1.92 gb of available memory, so I ended upgrading to win 10 64 bit, which installed and ran much better ( especially after deleting all windows apps and turning off all updates)
When they say it has been tested with windows 10 64 bit they really mean you'l be wasting hours with anything else
I believe some of the NUCs have had the option to disable USB3.0, forcing USB2.0 operation. This might work to get you started and set up, and hopefully you could re-enable and install USB 3.0 drivers once you're set up with Windows. However I do not have the NUC5CPYH or an updated BIOS/UEFI overview available at the moment, so I don't know if this option is available for the NUC5CPYH.
If not, here is how some other users have solved this issue, with good reports. The linked post beneath contains a link to a step-by-step guide, and details on what needs to be modified for different versions of Windows to be installed (the /index:# switch). This step-by-step guide actually applies to your scenario (Windows 7 Professional), so in your instance just follow the guide to "the letter". The guide is quite well formed, so I see no advantage is recreating it here.
Avoid installing 32 bit Windows unless you really need it, it imposes unneccessary restrictions (limit on addressable RAM ammount among others) when installed on your 64-bit NUC.
If this solved your problem, please mark the thread as solved.
I did eventually get it to work with 64 bit. I went back through the injection process and noticed error 5 when injecting the drivers to the install.wim file. After searching this I found it's caused by the driver files being locked. You have to right click each file individually and click the un-block button. The drivers then injected without any error and the install worked. It didn't work with 32 bit though but I can live with that.
Thank you for contacting the Intel Communities.
I am glad to hear that you were able to get it to work.
The recommended steps while installing Windows 7* in a NUC that only has USB3.0 would be to access the BIOS and disable the xHCI from Devices>USB, this would "make" it USB 2.0 which would allow you to use the keyboard and mouse.
The reason behind this situation, which you may know already, would be that Windows 7* installation file doesn't have the drivers for USB3.0, this would cause the disconnections or malfunctioning from USB3.0
Do not hesitate to contact the Intel Communities again if you encounter with any additional or new inquiries you may encounter with.