Buzzing/Humming from bottom left side of iMac?

I made a recording of my comp. Rev A 17" 1.8Ghz with 512MB ram. This thing is friggin' loud.

http://rapidshare.de/files/8117266/iMacG5-CG.m4a.html

Using Garage Band to record (I know it's not ideal due to it's processor-hungryness) I logged the following in XRG:

CPU Temp: 65.4 C
Hard Drive Temp: 42.5 C
CPU Fan: 3891 RPM
Hard Drive Fan: 2000 RPM
System Fan: 2370 RPM

My CPU isn't exceptionally warm, the fan is just running really hard. I'm going to pick up another 512 stick sometime next week to see if that helps any, as I know 512MB is considered the bare minimum for this OS.

Upon quitting Garage Band, iTunes, and Adium, leaving only Safari, XRG, and the finder running, and letting the computer sit with only the aformentioned applications open for approximately 5 minutes, the new XRG stats are:

CPU Temp: 64.5 C
Hard Drive Temp: 43.5 C
CPU Fan: 3047 RPM
Hard Drive Fan: 2000 RPM
System Fan: 1894 RPM

The system is still annoyingly buzzy. The sound only diminished slightly from when garage band was open. I believe there might be something wrong with whatever is driving my CPU fan, as the actual CPU temperature isn't abnormally high, the fan is just running way too fast. I'm going out this weekend (hopefully) to pick up a can of compressed air to blow out any soot left from my fried PSU or leaking capacitors. If that doesn't help, it's out for a new 512 stick I go. I'll keep you guys updated

iMac G5 Rev. A 17" 1.8GHz 512MB Ram 10.3.9 Mac OS X (10.3.9)

Well, I stuck another 512 in there, bringing the total up to 512 x 2. No help. After resetting the SMU, PRAM, and NVRAM, the problem has not gotten any better nor worse. I don't know if the certified apple repair center will accept my computer for fixing this, as it is a year and a bit old, and without applecare. I can't get the fan out of my Rev. A without taking out the motherboard, and Apple has convieniently pulled all instructions on how to do this. Grr. Hopefully I can get this fixed

iMac G5 Rev. A 17" 1.8GHz 1G Ram 10.3.9 Mac OS X (10.3.9)

One of the suggestions given at ScienceMan (http://scienceman.com/pgs/00imacG5fanforum.html) was to attach a piece of foam to the cpu fan housing. Apparently, the worst of the noise is caused by the fan housing resonating. I would think that a thick enough piece of foam could be held in place by simply sandwiching it in between the fan housing and the back of the unit. I have a 17" revision A with the whining fan and I plan on giving this a try. I'll post back with my results.

Mine sounded just like that!!! I think they've replaced everything they could on mine which has improved things a bit. They replaced the logic board along with the upper and lower fans. That took about 5 trips to the apple store. The noise level was reduced but I was still not satisfied. I called the toll free number yet again and they ended up mailing me a new hard drive (or it could be a refurb) which I got yesterday. I set my processor to automatic instead of highest and the temp is about 5-7 degrees lower. The noise level has reduced significantly but the whine is still there.

It's too bad that you don't have applecare though because the logic board is $735.00 and a replacement HD (250gig) is like $400.00.

I am so exasperated right now... I'm getting that fan revving on every click of a link whist surfing the net. I've not even put it thru any real work yet. The remote airplane analogy is so true (wherever I read that out here)

I also don't want to get into any back and forth with the Apple store - I just want a quiet unit. From the sounds of it, visits to retail are not 100% satisfactory. In their busy store enviro, there's no way they're going to hear the fan go.

Could there not be a f/w solution being that this is somehow tied to the cpu??

H!

iMac G5 2.0 BT AE Mac OS X (10.3.4)