Hello,i got a nvidia 8400gs hdmi awhile ago and when i go to control panel for sounds and audio devices it says there are none. i looked and the devices it came with a nvidia high definition audio thing but i don't no how to work anything to work if have been looking on the web but cant find anything please help!! + when my old graphics card was in there was sound.I re-downloaded Realtek High Definition Audio and installed it still nothing.
Your Nvidia 8400gs is your video card. I am not sure what your "Nvidia high definition audio thing" is... is it properly installed? try removing it and reinstalling it. what motherboard do you have? You may have to disable your on board sound for your "thing" to work