New Monitor No Sound from HDMI

I also found this in seven forums: Nvidia HDMI (greyed out), video, but no audio - Windows 7 Help Forums

Go to "Services" not Task Manager:

Arily said:

Thank you for that going to try it. So stop it first then set it to manual? Should I restart the computer after I do that?

If it doesn't show up after turning on, you could try a restart(won't hurt anything, but restarts are always good for the system) , I personally never had this exact problem., so it's somewhat new territory for me too.

Arily said:

I shut down my computer every night so I don't have an issue with it being on for long periods at a time.

I mentioned that, because many people(including my self) use Fast startup(in power options >> choose what the power buttons do) and that is not a "real" shutdown like the one in Win+x. I saves the last state to the hiberfile to boot faster, and changes that need to be made from a cold boot are not made until a restart is initiated(which shuts the PC all the way down).

Arily said:

Ok I set the nvidia service to manual stopped and started it and restarted the computer and still no sound and HDMI output still says not plugged in.

Sorry for the late reply. I'm out of ideas right now, maybe someone else will chime in that had this problem and fixed it.

I just thought of one more thing to try(just had my morning coffee)
Try unplugging all sound devices except the HDMI cable, and run the sound troubleshooter in Control Panel\All Control Panel Items\Troubleshooting\All Categories: