Sometimes cooling a system without overclocking can increase system stability
http://www.macmod.com/content/view/533/2/
with Adjustable DIP switch
http://www.xlr8yourmac.com/systems/sawtooth_bus_overclock/sawtooth_bus_overclock.html
You'll need a regular screwdriver, a small philips, a torx-8 and for step 22 a torx-6
http://homepage.mac.com/sysop/PhotoAlbum3.html
USB Ports Mod
http://www.xlr8yourmac.com/systems/G4_tower_front_fw_ports/G4_tower_front_fw_ports.html
Why put a G4 in a 9600 case? Two reasons really
http://www.xlr8yourmac.com/systems/g4_agp_in_9600_case/G4_agp_in_9600case.html
stick your thumb nail between the gap under the infra-red port where the two halves of the plastic case meet.
http://www.r3uk.co.uk/content/view/57/62/
how to overclock the Quicksilver Power Mac
http://www.macmod.com/content/view/75/2/
Want to make a cool G4 with out changing your stock case or adding a bunch of expensive fans?
http://www.macmod.com/content/view/188/2/
Replacing the Flyback Transformer
http://www.macopz.com/columns/imacrepair/index.html
replacing the controller
http://www.sterpin.net/uk/fwclamshelluk.htm