Infinite Loop / The Apple Ecosystem

Dual 2.5GHz Power Mac G5


Keeping your cool

No review of the Dual 2.5GHz G5 is complete without some discussion of the cooling system. The G5 is one of the first desktops to ship with a liquid cooling system standard. The need to keep the CPUs and other components cool was evident when the original G5s shipped in the summer of 2003. Apple designed the G5 towers with four distinct cooling zones, according to their product literature, which is why there's a lot of empty space and not a lot of room for extra components.

The PowerPC 970FX in the Dual 2.5GHz G5 is a 90nm part, and runs rather hot as a smaller die space means more concentrated heat problems. To deal with the high operating temperatures, Apple went with a liquid cooling system. The pipes carry a coolant which is heated and rises through the pipe. It then passes through the grille, where air blown over it by the fans cools it off. It then recirculates over the CPUs. Below are some pictures of the G5's cooling system, courtesy of

The underside of the cooling system

A rear view of the grille

A side view of the cooling system. Auto parts company Delphi is rumored to be the manufacturer

The removable fans pictured below are responsible for blowing air on to the grille.

You can't cool a computer without fans

It works well, and the combination of automatically-controlled fans and liquid cooling make for a surprisingly quiet computing experience.

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