mormegil,

Thanks so much for taking so much time to help me. I'm still not sure what I was doing wrong with the codec patching, but my solution turned out to be voodooHDA 0.2.2 64bit, installed in /System/Library/Extensions, and rebuilding the Extensions.mkext. I'm not sure which of the above did the trick, but one of them did, and my laptop is no longer silent.

For purposes of documentation, I have a Clevo M570RU-U, with an Intel 965 chipset, and a Realtek ALC883 codec.

Thanks!