Gigabyte EP45-DS3L - no audio

I have a weird problem with my new setup - it's a Core 2 Duo system built around a Gigabyte EP45-DS3L. Everything is working with a retail install except for audio. The audio codec is an ALC888. Sound works in Windows Vista and Ubuntu 9.04 without additional patches.

My first attempt to get sound working was using HDA enabler and an EFI string. That didn't do it.

Then I starte grabbing ALC888 kexts from anywhere and everywhere, none of them showed up after being isntalled with Kext Helper.

After that, I got an Ubuntu live CD (where, as I mentioned, sound was fine) and got a codec dump, and patched the retail kexts using HDA Patcher 1.20.

None of this has worked so far. But what's REALLY weird is what lspci reports...

01:00.1 Audio device [0403]: ATI Technologies Inc Radeon HD 3870 Audio device [1002:aa18]

WTF?! And that's the only audio device listed. I know the Radeon 3850 (it reports it incorrectly) can support audio over HDMI, but could that possibly be interfering with my motherboard's built-in audio in OS X when Windows and Ubuntu are OK? I actually went out and spent $20 on a DiamondMM Xtreme Sound which uses a CMedia codec. If I can get that to work I might just leave well enough alone, but this is friggin annoying.