I bet you didn't know this - but there's another company interested in reducing the noise of G4's with great temperatures. Dangerden!

I've been working with Danger den closely to create the first ever water-cooled Macintosh kit. We're still in a lot of prototyping - but I thought I'd give you a peek at one option were looking at. These kits will be for more of the "extremists" who want to go the extra mile. Weather it be over clocking, silence, or a really cool look.

Here's a few pictures ... With this and the apple power exchange installed in my Mac- the noisiest thing is my NVIDIA Ti Card's little fan. I believe it runs under 30dbl. Were currently working to improve this and make water-cooling the quietest alternative available for the Mac.
-Stephen Walker

Although Steven didn't include their URL, DangerDen's website is http://www.dangerden.com/.-Mike

Update: Gregory V. sent a link to a UK site article on Watercooling a MDD Dual G4 tower.
Kenneth P. also sent links to a mac parts dealer's listing of Adapter Kits For Mac G4s and Cooling Blocks as well as Liquid Cooling Systems.

For other MDD System related articles (mods/cooling/noise reduction, more) see the Systems page.