Dell XPS8910 on-board audio not working

What do you show in the Device Manager, for the audio?  Is Realtek or "High Definition Audio" listed?  and is there any error showing? 

Windows will usually install the Realtek on a new install, if the sound is enabled and the chip detected.  If Windows does not properly detect Realtek it may install the generic High Definition audio driver, but the speaker jack and headphones usually work.  Windows will usually also install any motherboard (Intel in this model) chipset drivers (which must be installed for Windows to detect devices such as audio).

Download and manually install the Intel chipset drivers and Realtek and see if that helps.

http://www.dell.com/support/home/us/en/19/product-support/product/xps-8910-desktop/drivers

Device Manager shows both NVIDIA HD Audio and Realtek Audio. Realtek is apparently working properly. As mentioned earlier, I disabled NVIDIA audio.

When I did the clean Windows 10 install, both NVIDIA HD Audio and Realtek Audio drivers were downloaded and installed by Microsoft. I'd already tried reinstalling Realtek audio drivers from the Dell website, but no improvement has been found.

If I use the rear jacks I get nothing from my speakers unless I turn the volume up, then I get feedback. The input jacks don't function at all.  I believe the front jacks may function, but there is background hum.

I'll now look at the Intel chipset drivers...

I missed part of your original post, sorry.

Since you have Realtek installed but Windows has defaulted to HDMI audio, can you set the "Speakers" (Realtek) as default audio playback device?  In most cases, if there is an HDMI connection then Windows will set HDMI as default audio playback device.   In my own system, I'm using a Dell monitor with HDMI connection but I have the HDMI audio disabled in the Device Manager and that keeps Windows from defaulting to HDMI audio. 

The usual recommendation is to install the chipset driver first after a clean install of the OS. If you have not done that I recommend that you do that before installing the other drivers. 

Thank you for your assistance. 'Realtek Audio' appears in both recording and playback device lists and I had made then default devices. The rear jacks just don't function, even though 'Properties' says they are 'working properly'.

I had hoped there was an option in the BIOS to force the PC to use on-board sound, but that doesn't seem to be an option with this PC!

Thanks for that advice. I downloaded the 'Intel Chipset Device Software Driver' and reinstalled Realtek and definitely have a vast improvement! I still have issues with some Roxio sound recording software, but assumed I'll need to reinstall that as well.

Are there any other bits of Dell software that I need to install? The only issue I had with the PC was audio.

Thanks to all for your helpful support - much appreciated!

I am happy it worked out for you. As far as other Dell software, I would consider network, WiFi, Bluetooth, and Intel Management Engine drivers only since Dell seems to provide these vice letting Windows decide which to use. For protection you could create a system restore point (Control Panel/System and Security/System/System Protection/Create) to undo unwanted system changes in case something goes wrong.

Thank you!