Drive-Bay Fan Chirp: Here’s a short recording of the chirping noise made by the squirrel-cage fan in the drive bay of my first-generation G5 2x2. Turn the volume up if you don’t hear the squeak. (See Recording Details and updates below.)
The chirping sound is intermittent, usually beginning after the G5 has been awake for an hour or more. Time appears to be the triggering factor, and I haven’t detected any heat issues using Hardware Monitor. When the fan is chirping, the chirps come once per second, easily timed using the analog clock on the Mac.
Though this recording was made with the aluminum door open and the microphone in the approximate location of the camera lens in the photo, the chirping is noticeable when the door is closed. (Ears are much more sensitive to the high frequency of the chirp than cheap microphones.)
It’s clear that this sound is not the same as the well-known G5 processor chirping. (See Processor Chirp below.)
Moving the hard drive from the upper slot to the lower slot may have reduced the problem, but did not eliminate it.
The temperature sensor for the drive bay is attached to underside of the top of the G5 case at the right rear corner. You can cool the sensor by cooling the outside of the aluminum case at that spot, for example with canned air or a cold-pack. With enough cooling, I think the squirrel cage fan turns off. But when it restarts a few minutes later, the squeak returns.
New Hard drive Update: I recently had to replace my hard drive, a Maxtor Calypso, which suddenly started making this noise. Since replacing the drive (with a Maxtor 7Y250M0 that AppleCare sent), I have not heard the chirp described above. A week later, the chirp is back, still very intermittent. I think that eliminates the hypothesis that the drive itself is making the chirp noise.
It might be a good idea to replace any Maxtor Calypso drives now, as a precaution, given the low prices of 250 GB drives.
Tiger Update: OS X 10.4 certainly seems to have made a difference. There’s clearly less squeaking when running in Tiger than in Panther. In Tiger, the fan squeak seems start later and to be much more intermittent, so I’m much less bothered by the fan chirp.
OSX 10.4.3 Update: 10.4.3 definitely brought back a fan-related problem that G5 owners saw in early 2005. The symptoms are that the processor fans seem overly sensitive to processor use, revving up somewhat noisily for a few seconds seemingly at random. This is being widely reported by G5 desktop owners in November. Coincidentally, I think I notice an increase in drive fan chirping since installing 10.4.3 (as compared with 10.4-10.4.2).
Processor Chirp: Marcel Bresink’s SystemLoad can play a scale using the processor squeak. Grapher, a new utility supplied along with Tiger, can exercise the processors (try the Conchoid demo). Another way to hear the processor squeak is to drag an e-mail message to the mailboxes bar in Mail 2.x and--still holding the mouse button down--drag the message up and down as if searching for the right mailbox. Here’s an Apple Technote on the processor chirp and other noises: Power Mac G5: I hear buzzes, beeps, or humming
Recording details: I recorded the fan chirp with the built-in microphone of a hand-held Sony portable tape recorder, then rerecorded from a tape deck to Sound Studio. I applied the Normalize filter at 85% and the High-Pass filter at 4000 Hz, followed by Normalize again. I then imported the AIFF into QuickTime Player and exported the sound sample from QuickTime Player with the QDesign Music 2 codec, which mutes the background noise a bit more.
If you have questions or information on this fan issue, please e-mail me.
Updated