Crackling sound only occurs when playing DVDs in either of my DVD drives, DVDs on the HDD play OK. I have searched the internet for a cure to this one and read lots of complicated suggestions about drivers and patches, none of which seem to work for anybody. In the end disabling the firewire on my motherboard completely cured the problem. (Gigabyte GA 7N400 Pro). I would suggest disabling other unused on-board hardware items in the bios, may also cure the problem.