ok, so i'm not sure if this is just a coincidence or not just yet, but after uninstalling LCC (logitech control center), my fans have been acting NORMAL! for HOURS so far! constant, loud fan noise is an issue i have been having for a very long time, and apparently so have many other G5 owners. during my search for a solution, i came across several webpages full of posts from users in distress over the same problem i was having. apple tried replacing the logic board - nothing. tried pram reset - nothing. tried creating a new user account - nothing. couldn't use smcFanControl because of the PPC chips. long story short, i gave up on it and just suffered through the annoyance of having fans that were louder than any music, movie or game being played at a normal volume. i can't believe that in all my searching for an answer that i never came across anything that suggested i uninstall my logitech mouse drivers. so i guess that's why i'm posting this.. for others who may be having the same problem and nothing else has worked, hopefully google can help them find this thread. if you are using logitech drivers for your mouse or keyboard, uninstall them! i switched to SteerMouse about six hours ago and haven't been disturbed by my fans since then. hopefully this is the real deal! i'll post an update if the problem comes back.