Thanks for joining the Graphics community.
I understand that the monitor connected via HDMI does not go to sleep.
At this stage, make sure you have loaded the latest video drivers for your graphics controller here: Intel® Download Center File name: Win64_153322.exe
The last part of your post says that working with Microsoft generic video drivers is the same. This is an indication that this is not a driver problem. The problem might be the port itself or the motherboard BIOS.
See the following link for BIOS download: ASRock > Z97 Extreme6
Thanks
Allan.