EVGA z170 FTW with latest BIOS. Telling Windows to Sleep will begin to power down and then immediately resume. Event log says something about a HAL error: Microsoft-Windows-HAL 12 None The platform firmware has corrupted memory across the previous system power transition. Please check for updated firmware for your system." I can only find instances of people with the same HAL error being reported when S3ing but NOT actively disrupting Sleep. And yes, WOL is disabled, and S3 is enabled in BIOS. System performance is normal otherwise.
Not sure if it will help you, but every time I switch motherboards or plug in a new device my attempts to sleep end the same way. I always have to go into device manager and manually open EVERY SINGLE item that has to do with any kind of device, open properties for every single item and then go to the power management tab and uncheck all the boxes. Without fail, assuming BIOS/UEFI settings are correct, this has always allowed my PC's to sleep properly. I am currently enjoying success with this method on an X38, Z68 and Z97 so it seems like it may work with your Z170. Good luck and feel free to ask for more detail.
