Here's a solution For users of Optiplex GX620 Ac97 sound cards or similar cards. The card i Have is, specifically: Intel 82801G (ICH7 Family) AC'97 Family Sound Card (Integrated) (rev 01) (Dell Device 01ad). Download this kext, http://www.insanelymac.com/forum/index.php?showtopic=88597. Place it in your home folder. Choose Go>Go to Folder. paste this in : ~/AppleAC97Audio.kext/contents/plugins/AppleAC97AudioIntelICH.kext/Contents . Double-click Info.plist (you must have read-write access to all parts of the kext.) you could also type, in CLI, " nano ~/AppleAC97Audio.kext/contents/plugins/AppleAC97AudioIntelICH.kext/Contents/Info.plist " search for the following lines of text (usually the first result for the string 0x266e8086) <string>AppleAC97AudioIntelICH</string> <key>IOPCIPrimaryMatch</key> <string>0x266e8086</string> Make it look like this. <string>AppleAC97AudioIntelICH</string> <key>IOPCIPrimaryMatch</key> <string>0x27de8086 0x266e8086</string> Install the kext with the standard procedure. If the kext doesn't already exist, u can use kexthelper. Remove a kext that already exists in the /System/Library/Extensions directory (you'll need "root" privleges) with the same name, but back it up to a safe spot first. Then install your new, modified, kext. Now sound works, including Front panel outputs on the GX620. Success may vary with other models. This fix is confirmed working on 10.4.6, 10.5.6, and 10.5.8. I have personally used it on the latter two. I will report shortly whether i have success with 10.6.2. Update: Confirmed in 10.6.0 and 10.6.2. Works fine.