[CentOS] Another system with no sound

I am also having an issue with no sound on some CentOS desktop systems.  I manage about 3 dozen desktops.  These are all Lenovo ThinkCentre systems of varying vintages, but there are only 2 distinct sound controllers among all of them:

00:1b.0 Audio device: Intel Corporation 82801H (ICH8 Family) HD Audio Controller (rev 02)
00:1b.0 Audio device: Intel Corporation N10/ICH 7 Family High Definition Audio Controller (rev 01)

On some systems, the sounds is working fine, and on others it's not.  It's not a sound controller issue, as I've got sound working on multiple systems with each controller.   I've checked the settings in alsamixer and the master is not muted.  As far as I can tell, all systems are configured similarly (they were build via kickstart and maintained up-to-date with "yum update" periodically).

Here is some info from a system on which sound is working:

# lspci | egrep -i 'audio|sound|snd|alsa'
00:1b.0 Audio device: Intel Corporation 82801H (ICH8 Family) HD Audio Controller (rev 02)
# lsmod | egrep -i 'audio|sound|snd|alsa'
snd_hda_intel         523949  0 
snd_seq_dummy           7877  0 
snd_seq_oss            32577  0 
snd_seq_midi_event     11073  1 snd_seq_oss
snd_seq                49585  5 snd_seq_dummy,snd_seq_oss,snd_seq_midi_event
snd_seq_device         11725  3 snd_seq_dummy,snd_seq_oss,snd_seq
snd_pcm_oss            42817  0 
snd_mixer_oss          19009  1 snd_pcm_oss
snd_pcm                72133  2 snd_hda_intel,snd_pcm_oss
snd_timer              24516  2 snd_seq,snd_pcm
snd_page_alloc         14281  2 snd_hda_intel,snd_pcm
snd_hwdep              12869  1 snd_hda_intel
snd                    55877  9 snd_hda_intel,snd_seq_oss,snd_seq,snd_seq_device,snd_pcm_oss,snd_mixer_oss,snd_pcm,snd_timer,snd_hwdep
soundcore              11553  1 snd

And here is the same info from a system where sound is not working:

# lspci | egrep -i 'audio|sound|snd|alsa'
00:1b.0 Audio device: Intel Corporation 82801H (ICH8 Family) HD Audio Controller (rev 02)
# lsmod | egrep -i 'audio|sound|snd|alsa'
snd_hda_intel         523949  1 
snd_seq_dummy           7877  0 
snd_seq_oss            32577  0 
snd_seq_midi_event     11073  1 snd_seq_oss
snd_seq                49585  5 snd_seq_dummy,snd_seq_oss,snd_seq_midi_event
snd_seq_device         11725  3 snd_seq_dummy,snd_seq_oss,snd_seq
snd_pcm_oss            42817  0 
snd_mixer_oss          19009  1 snd_pcm_oss
snd_pcm                72133  2 snd_hda_intel,snd_pcm_oss
snd_timer              24516  2 snd_seq,snd_pcm
snd_page_alloc         14281  2 snd_hda_intel,snd_pcm
snd_hwdep              12869  1 snd_hda_intel
snd                    55877  11 snd_hda_intel,snd_seq_oss,snd_seq,snd_seq_device,snd_pcm_oss,snd_mixer_oss,snd_pcm,snd_timer,snd_hwdep
soundcore              11553  1 snd

Similar, but not quite identical.  The settings in alsamixer, however, are identical.  Any ideas as to what I can try next?

Thanks,
Alfred