What kind of sound card is on board? 2.1, 5.1 or 7.1
Just a simple analog audio on-board "sound card" circuit. Likely a Realtek or similar. No one really does (analog) 5.1 that way any more. You can Bit-Stream digital 5.1 over SPDIF (if it has the port ... see PDF manual). You can also Bit-Stream DD/DTS 5.1/7.1 over HDMI. Most people use HDMI for Multi-Channel PCM ... up to 7.1 channels.
Pretty sure any audio over HDMI only uses the video card. HDMI to a nice AVR works good.
Seems many doing Digital Audio Work these days are using USB "sound cards". In that case, on-board audio goes un-used.
Registered Microsoft Partner and Apple Developer - Like many of you, I can appreciate a good game-engine. - I answer questions here, but I'm not a Dell employee. - Consider giving posts you like a "thumbs-up" - Posting models-numbers and software versions speeds trouble-shooting. - Click "Accept as Solution" button on any post that answers your question best.