G5 Noise recordings
These recordings were done with a headset microphone put very close to the computer.
To put it into relation: my voice came from about 30 inch away,
while the computer was right at the microphone.
G5 noise - long recording and me describing what i'm doing (1.7 MB MOV)
(sorry for the slow and interrupted talking in the recording, but i'm no native english speaker)
OpenGL-induced whine noise only (260 kB MOV)
Note that the sound right after the beeping is not caused by the fans.
They turn on a bit later. Also note, that the sound completely stops if
"CPU napping" is turned off. See the long recording for an example of that.
The microphone was placed about an inch away from the bottom front of the machine.
It's a very quite computer, all in all, but because of that,
the chirping and whining sound is even more annoying.
A louder machine would possibly drown it.
M. Altendorff, Nov. 15, 2003
Video, oscilloscope readout from USB port voltage (front panel - 969 kB MOV)
This shows the high frequency noise that comes with the 5 volt supply of the USB port on the front panel. The recording starts with the pretty clean signal while the CPU is idle, then the Cinebench OpenGL HW-Light sequence is launched.
This was a quick-and-dirty test, and we had some trouble setting up the oscilloscope (and found the X-axis and trigger was broken, so this was the best we could get). I can't even tell which amplitude this noise has, just that it's there on both USB and Firewire connectors and that it does respond to the "napping" setting and the CPU load.
Definite results would require to measure each line that comes from the PSU to see which output is most affected.
M. Altendorff, Nov. 25, 2003