Karmic Koala and sound on the HP DV6105us

I attended the Karmic Koala release party at the kwartzlab and had the opportunity to upgrade my laptop from the local repository.

Everything went well except for the sound on the laptop. Thankfully the alphas, betas and RC periods are for people to find these issues and provide workarounds :D.

My card is identified by lspci as

00:10.1 Audio device: nVidia Corporation MCP51 High Definition Audio (rev a2)

The problems were:
- Sound didn't work
- Sound made a crackling sound.

Both were very easy to fix once I found the answers:

To make the sound work
It seems that something from the previous version was causing trouble.

http://ubuntuforums.org/showpost.php?p=7811407&postcount=10

The solution is to delete ~/.pulse and restart pulseaudio
rm -r ~/.pulse
killall pulseaudio

To stop the crackling (clicking) sound
http://swiss.ubuntuforums.org/showpost.php?p=8099760&postcount=12

Those clicks are caused by the power saving option introduced in karmic. The solution is to comment the powersaving line in /etc/modprobe.d/alsa-base.conf

The line I commented out is
options snd-hda-intel power_save=10 power_save_controller=N