I have an iMacG5 revA, and recently I have been experiencing the noisy environment when the fan of the cooling system start to turn full speed as soon as you provide a bit too much tasks to the CPU. But, then I remember your article in September 2005 about the G5 cooling system trapping all the dust around.
So, being not really well equipped, I nevertheless decided to clean up the heatsink of the G5 while disassembling the minimal amount of my iMacG5. So after opening the case, I removed the cover of the heatsink located on the CPU, then I blew very very strongly through the copper-based output. On can see on the last photo the dust went out via the inlet and got trapped by the case; after using my vacuum cleaner to remove it, then reassembling the case, my iMacG5 is back to silent!
The best solution would probably be to use a dry-air spray from the outlet while applying a vacuum cleaner on the other side. We recommend to clean up the heatsink of your iMacG5 in order to preserve it longer, it will keep your CPU cooler.
