So last night I decided to give my PowerMacs 1.8dp (pci ver) rear exhaust fan a good cleaning...unplugged it and took it out cleaned,replaced....Now the top exhaust fan is on full power (sounds like a jet ready for takeoff...errrrrr) all the other fans including bottom exhaust fan running as per normal. What do I do? -Ive tried all the normal routines,reset PMU,Pram ect...nothing! I've read about needing some apple "Thermal calibration dvd"??? If so,what # and where do I get it?