Recently my Shuttle HTPC started having issues when booting into Gnome using any sort of hardware video acceleration. I would turn it on and watch it boot until it got to the login screen, at this point it would either let me login and then power off or just power off before it got to the graphical login screen.
I decided to pick up a new video card with HDMI so I wouldn't have to switch my speaker input to direct each time I wanted to use my PC. I grabbed the EVGA GeForce 210 from Tiger Direct and after some power setting changes in the BIOS, the computer booted and automatically started using the newly plugged in HDMI cable!
Now all I had to do was get the sound working. To get sound output, I first needed to turn off the onboard HD audio from the BIOS because it is also made by nVIDIA and will cause problems when trying to get the sound going.
Next I found a great thread (http://forum.xbmc.org/showthread.php?t=69601) for XBMC and how to setup HDMI audio. Their config sort of worked for me but I had to change a few things.
Please note that this is for Fedora.
First I noticed that the prerequisites for their version required alsa 1.0.23 drivers. Fedora only had 1.0.21 by default so I needed to grab packages from ATrpms.
I added the repo for yum as follows:
Create the file /etc/yum.repos.d/atrpms.repo with the following contents:
[atrpms] name=Fedora Core $releasever - $basearch - ATrpms baseurl=http://dl.atrpms.net/f$releasever-$basearch/atrpms/stable gpgkey=http://atrpms.net/RPM-GPG-KEY.atrpms gpgcheck=1
Then you can run
[root@tclarrltp ~]# yum install alsa-driver
Install any dependencies that are required.
Next you need to configure the hd sound module to work properly. As it stands right now, your machine will probably tell you that it has 4 SPDIF outputs for the card, this will not work so we have to change it.
Create the file /etc/modprobe.d/sound.conf with the following contents:
options snd-hda-intel enable_msi=0 probe_mask=0xfff2
Now reboot your machine, a quick look at /proc/asound/version should show that the drivers are now at 1.0.23.
At this point you should have some sound, but if you don't fire up alsamixer and change the soundcard to the nVIDIA card and see if the line is muted. If it is muted, just press "m" to unmute.
And that should be it! If you are still having trouble with this, leave a comment and I can try and work through it with you.