Ok here go's: Running OS 10.5.7, no dual boot. Have a mac mini 1.5ghz solo. I have upgraded the ram (about a year ago) replaced the internal hard drive about a month ago. So I am no stranger to getting inside and working on the mini. I bought a 2.13 Ghz Duo Core processor, swapped the 1.5 single out and put the machine back together. I get no audio. System profiler says no audio. In the audiio/midi setup it shows unknown device. Everything on the audio side is grayed out. Things I have tried: Took machine apart put back together 3 times to make sure everything was seated. This included the brownish red ribbon cable that I understand is the audio card connection. Also all the small black wires for the fans, and system light. Tried resetting Pram Tried resetting SMC Tried an apple update. Tried deleting all my midi settings. Not sure where to turn..I have read every post I can find on this subject. All pertain to 10.4 typically the smc reset or a reseat of the ribbon cable fixed the issue. I have a firewire based audio input on the way (m-audio 410) but I would like to have onboard audio working again.