I have a G4 cube which I installed an IDE SSD 

It is totally silent now. I do have a Sonnet G4 1.25 processor upgrade but it has a fan on it which would introduce noise so I didn't install it.

I relegated my cube to OS X 10.3 and have it connected to an Apple Laserwriter writer. I was pleased that Apple used Apple Talk in OS X 10.3 as it was the last OS to support apple talk and apple printers.