These are our recommendations for this issue:
*Please check the HDMI cable you are using is 1.4a, since this is the only one that support audio and video.
*Try installing the latest audio driver available:
*plug a headset directly to the motherboard and check if you are able to get sound from it.
* install the latest BIOS version available for your motherboard https://downloadcenter.intel.com/SearchResult.aspx?lang=eng&keyword=Intel%20Desktop%20Board%20DH87rl&DownloadType=BIOS
Same situation here, just got a DH87RL version AAG7240-403. I do not see the HDMI device in the Realtek Audio Control Panel. With a previous PC based on Gigabyte using exactly the same cable hooked up to the same TV I had no problems. Going back to an older version of the graphics driver(Win64_153117.exe) did not solve the issue.
Hope this gets solved, like what should happen with USB 3.0 sticks and keyboard leds.
Whispergear, our engineering department is already working to get this issue solved. I still do not have an estimate time of resolution but you can keep checking the following thread for updates. https://communities.intel.com/thread/46737?start=15&tstart=0