Question Audio via HDMI for Dell S2415H only works sporadically

[Grace_Omega]

I've had a Dell S2415H monitor for several years. During that time, I've never been able to get audio through HDMI via my GPU (GTX 970) working. Last week I mounted the monitor to a clampy arm thing (this one) and got a tp-link USB bluetooth adapter (this one). Following this, HDMI audio started suddenly working...sort of.

Sometimes it works and sometimes it doesn't, seemingly completely at random. If it's working and I put my PC to sleep, it will stop working. I've noticed that sometimes if I've been using my headphones via bluetooth and disconnect them, my speaker audio will start working, but it's not reliably reproducable. The HDMI audio option is called "Dell S415H-2 (4-Nvidia High Definition Audio)". I've tried setting the monitor as the default audio device in the Windows control panel and setting the monitor as the selected audio device in the Nvidia control panel. I've also updated my GTX 970's drivers several times.

While fiddling with audio settings (enabling and disabling the monitor in the control panel etc) I noticed that my current audio device in the taskbar volume thing was switching back and forth rapidly between the monitor and "Digital Audio (High Definition Audio Device)". Not sure if that's relevant.

Also not sure if it's relevant but there's several inactive "Nvidia output" devices listed in the sound control panel. It looks like this.

Does anyone have any idea what's going on here? When I got the monitor I assumed the speakers were just broken, but apparently they aren't.

Full specs in case it matters:

MSI Z87-G45 Gaming mobo
i5-4670K
GTX 970

I should also mention that I'm currently using a completely fresh reinstall of Windows 10, installed on a formatted SSD, although the behaviour was the same before the wipe and reinstall.

 

[Lutfij]

List your specs like so:
CPU:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:

Which version of (assuming)Windows 10 are you on? Might want to check and see which version of the BIOS your motherboard is on. Also take note of the version of the GPU drivers you're working with at the moment. Have you also tried connecting the display to a donor system via their HDMI cable to rule out a faulty cable and or issues with the drivers?

 

[Grace_Omega]

List your specs like so:
CPU:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:

Which version of (assuming)Windows 10 are you on? Might want to check and see which version of the BIOS your motherboard is on. Also take note of the version of the GPU drivers you're working with at the moment. Have you also tried connecting the display to a donor system via their HDMI cable to rule out a faulty cable and or issues with the drivers?

CPU: i5-4670K
Motherboard: MSI Z87-G45 Gaming
RAM: Corsair Vengeance DDR2 16GB (8GB x 2)
SSD: Samsung 840 EVO 250GB
PSU: Antec 550W 80+ Gold
Chassis: Corsair Graphite 600T
OS: Windows 10 64-bit v.1903

As far as I can tell I'm on the latest version of my motherboard and GPU drivers. I'm not currently using realtek audio driver though, I'm using whatever comes with Windows 10. Do you think I should try it? I've had bad experiences with trying alternate drivers, but I'll install realtek if it might help.

I went into the properties window for my monitor in the device manager (under audio) and found this, not sure if it's relevant or not:

Device SWD\MMDEVAPI\{0.0.0.00000000}.{91973af2-9844-446c-8e24-9c17559db842} was configured.

Driver Name: audioendpoint.inf
Class Guid: {c166523c-fe0c-4a94-a586-f1a80cfbbf3e}
Driver Date: 03/18/2019
Driver Version: 10.0.18362.1
Driver Provider: Microsoft
Driver Section: NO_DRV
Driver Rank: 0xFF0000
Matching Device Id: MMDEVAPI\AudioEndpoints
Outranked Drivers: c_swdevice.inf:SWD\GenericRaw:00FF3001
Device Updated: false
Parent Device: HDAUDIO\FUNC_01&VEN_10DE&DEV_0071&SUBSYS_14623160&REV_1001\5&344006e6&0&0001