DISCLAIMER:I have made this guide for people using ATI/AMD GPUs because that is what I have, because as-far-as-I-know AMD uses only one audio codec and because it's what I've tried and know, works. Still, the principle should be just as valid for NVIDIA or even Intel HD cards.My Build:.:27ud9cd4 Motherboard: Asus P5G41T-M LX PLUS.:27ud9cd4 CPU: Intel E7400, overclocked @ 3.37GHz.:27ud9cd4 Memory: 4GB Ram DDR3 1333.:27ud9cd4 Ethernet: Realtek RTL8169.:27ud9cd4 Audio Codec: ALC887-VD.:27ud9cd4 Graphics: XFX Radeon HD 5570 1GB DDR3.:27ud9cd4 OS: Mountain Lion 10.8.2I bought this Asus board a couple months ago and mostly it works very well. Now, when I bought it I looked at the audio codec but I didn't search for actual user experiences getting it to work (my mistake) and to my surprise, upon getting home I quickly realized that AppleHDA and my board just weren't the best of buddies.Flash-forward a couple of weeks and I'm resigned to using VoodooHDA. Now, VoodooHDA doesn't make friends with my HDMI audio so I have to choose between AppleHDA and HDMI or Voodoo and on-board and frankly, that sucks.The solution? Use both at the same time!Now, usually this will result in a kernel panic.

• Uninstall Kext

Uninstall Kext

Because by default both these kexts try to match devices by their PCI-Class and logically end-up trying to take control of the same devices and that's not good.But, with a few minor edits it's possible to have them both coexist peacefully.Normally, AppleHDA(AppleHDA.kext/Contents/Plugins/AppleHDAController/Contents/Info.plist) will have these lines near the bottom:IOClassAppleHDAControllerIOPCIClassMatch0x04020000&0xFFFE0000IOProviderClassIOPCIDevice. IOClassVoodooHDADeviceIOPCIPrimaryMatch0x27d88086 (0x8086:27d8 is the PCI Vendor ID for my on-board ALC887 device, you can check these by using 'System Info.app')IOProviderClassIOPCIDeviceNow Voodoo will know to try and match only your on-board audio and AppleHDA will know to try and match only your GPU's audio.Clearly, you're not yet quite done. For this to work, you will need more-or-less the same DSDT edits you would use to enable HDMI audio normally (and if you're using an AMD card like me, you need to be sure your Framebuffer is correct, which I won't go into now)The only departure from the tried-and-true DSDT edit for AMD cards is the following (I'm not entirely sure it is needed but I did it this way and it worked)You must add the layout-id that normally goes in the HDEF section to the HDAU section, like this. PathMapsPathMapNodeID3NodeID2PathMapID268610049 See?