Here is the tower on desk when I realized I couldn't take the noise any longer.

I decided to take a bunch of the cooling ideas from my PC to Mac conversion and apply to my G4 in hopes to reduce the noise and temperature in the case. So, I had to strip the case of everything. Note the CPU fan in the pic turned out to be the big offender - but I didn't realize that at first.

In process of removing everything...

All-in-all about 15 minutes to strip the case down. Not too bad.

Note the plastic washers around the feet of the speaker to raise the clearance from the case. Add a vent hole and air can now flow in the speaker port and around this assembly or through the hole I made.

Opening the back of the speaker for air.

My first thought was the 120mm case fan was the offender. As such, I...

removed the grill , cleaned and lubricated the fan.

I also cut out the exhaust section of the case and yes I did clean this up.

Why are all my best tools, older made in the U.S.A. models and why can't I buy them anymore?

The top of the case with hot air exhausts.

Bottom front with fresh air intakes and speaker port.

Bottom of the case with lots of holes for air to rise up and though the case.

I even made large holes in the HD bay so that air could more easily flow around the 2 120GB Maxtor 7200RPM drives.

120mm fan mounted back in case - look at that clear, unobstructed view.

It turns out I put the whole thing back together and it was still whining. I did some digging and realized the CPU fan was the problem. I took it apart and cleaned the bearings and then repacked them with fresh grease. The fan worked again and was quiet, but wasn't really moving air like it should. It was too little, too late. The bearings were just shot. So, I couldn't find a readily available replacement fan but found a ton of Delta Fonsan Fans for dirt cheap. I ordered up a set. Turns out they are a little smaller than the CPU fan, but they are the same height as the heat sink. I screwed 2 of them on the sink and combined the wires into one connector. BTW - the fans I ordered had the proper connector for the Apple motherboard. So here they are, they are quiet and keep the heat sink cooler than the original fan did.

Moved to under the desk and on some blocks to get the SuperDrive height up and improve air flow. The case is now super cool inside - and quieter - but alas, still not as much as I'd like. I am going to get a slower, quieter 120mm fan too. Will post that update here, later. If you are thinking of doing any of the above ideas, get the 120mm fan too before you start. You also should note I removed the back plastic from the case - it's grill over the power supply fan is not ok. I even removed the metal grill on the PS as I did with the large case fan. Happy Mac modding!