Unfortunately this problem is not new and still marked as unsolved. See these posts : https://communities.intel.com/message/317394#317394
and a simple workaround that in my case has succeeded.
INTEL, WHERE ARE YOU ?
Intel® does not test and validate Intel® NUC on Linux*. However, we have reports from a lot of NUC owners that are using it successfully on many different Linux* distros.
Intel® suggests checking your Linux* distro's website and forums at Linux Lite Forums - Index for peer assistance with this issue.
*Other names and brands may be claimed as the property of others.
I performed a test with the Intel® NUC Kit 5i7RYH and Ubuntu 15.04. The suspend mode is working without any issue.
Please, enable the UEFI and Legacy mode on the Boot tab; on Devices tab enable USB Legacy, enable xHCI. Both operating systems were kept on UEFI; please check the picture.
I performed the test using RAID 1 volume with Microsoft® Windows 10 64bit and Ubuntu 15.04
I agree that the suspend mode is working without issue. I use that every day. My problem was with the SLEEP mode; when the power saving settings kicked in. Please test the sleep mode. My unit was working normally for a couple weeks or more, then one morning woke up, tried to start the system and it wouldn't respond to keyboard or mouse. Then I discovered it wouldn't even respond to a press of the power button. I did some googling, saw others had been through the same issue, and realized I was screwed. I had to disassemble the unit, unplug the battery, etc., to get it operational again. I hope you can investigate that issue.
Please confirm which version of the BIOS is installed on your Intel® NUC5i7RYH.
Take into consideration on BIOS Version 0350 - RYBDWi35.86A.0350.2015.0812.1722 we fixed issue where system does not wake up from S5 using USB devices when BIOS option for Wake on LAN from S4/S5 is set to Stay Off.
Please confirm if you are currently using this BIOS version and settings are set accordingly.
I am currently running BIOS Version 0350 - RYBDWi35.86A.0350.2015.0812.1722. My system did have a faulty audio input and was replaced under warranty. At this time everything with my system is fine; I have audio and it wakes as expected.
FWW, I have UEFI boot configured and run Ubuntu 15.10 from an SSD and Windows 10 from an SSHD drive. My only current wish if is for an Intel/Ubuntu driver for the Intel Iris 6100 Broadwell GT3 graphics. It wasn't available last I checked.
I am glad to hear issue is now solved after replacing the faulty unit.
Additionally, in regards to the graphics drivers for Linux for Intel® NUC5i7RYH. Most versions of the Linux* operating system include Intel® graphics drivers. Intel recommends checking with your Linux distribution vendor or computer manufacturer for precompiled driver packages.
Some generic pre-compiled versions of Intel graphics drivers for Linux are available on the Downloads section of the Linux and Intel graphics* website. Support for these precompiled versions is only available through the open source community. See the Community section of the Linux and Intel graphics website.
Intel® does provide development drivers for Intel graphics to the open source community. These development drivers are intended to provide the Linux developer community with an opportunity to provide feedback on the driver and participate in its development.
Development driver source code can be obtained from public repositories found in the Downloads section of the Linux and Intel graphics website.
Development driver support is only available through the open source community. See the Community section of the Linux and Intel graphics website.
This is one of at least fourteen threads in this forum which address Intel's 'Linux Suspend > Dead NUC' intermittent defect, dating back to August 2014.
The good news is that a workaround exists which means you can at least avoid getting your NUC bricked by this defect, and it involves using methods other than a short press on the Power button to wake a sleeping NUC – ie: wake-on-USB and/or wake-on-LAN.
For full details, see the 'Workaround Alert' above the my OP in the 'NUC5i5RYH Bricked by Ubuntu Suspend for Fifth Time' thread » https://communities.intel.com/message/359708#359708