Hello, I am new to the Mac world but have been a fan of my PowerPC G5 for a year or so now. But lately the front upper fan has been constantly at full speed creating a loud whirling sound. I have done a full diagnostic with the start up disk, made sure there is plenty of open space around the tower, I have blown it out with an air can, and even repaired disk permissions and have ran some virus tools... nothing seems to work. This problem came out of no where and I need help as the noise is bothering everyone around me. Can anyone give me some advice?