What could this be?A bad SMC chip? That is what Apple says it could be, but what else could bethe problem? I have tried the following that Apple told me, but it remains: External Speakers(even louder buzz) Other earphones Checking for debris Everything is fine. Has anyone else experieced this. It has been here before the SMC FirmWare update. About to run apple hardware test. PS:Could it be something on the logic board?