There is a lot of complaining about the chirping noise that the PSU makes on the Dual G5, there is a thread on the Apple discussions that is has already 330 replies. Mine makes it as well... its very sad, cause the rest of the machine is extremely quiet. The chirping noise is very low, but if you have your machine right beside you, you can hear it perfectly. Its annoying, cause you have a such a nice machine, that looks like it has a very tiny cricket inside... However, I found a solution for this probelm. When I have Folding@home running, the chirping is completly gone! I know that installing CHUD solves the problem too, but this is a weird situation as well. Cause its not related to CPU intensive tasks (like running Folding). When Im doing intensive things on Photoshop and i have folding on, the machine is completly quiet. If i do the same thing on Photoshop without Folding running, the chirping from the PSU comes back. This happens on all the energy settings (Auto, Highest, Lowest). Odd... Can another Dual G5 user test it and see if it works for him/her as well?