You can see why Apple waited for the 90nm version of the PowerPC 970 before launching a G5-based Xserve 1U rackmount server: the latters heat dissipation characteristics. While Intel continues to have problems with the power consumed by its 90nm "Prescott" processor - 100W at around 3.2GHz - IBMs own documentation claims the 90nm 970 eats 24.5W at 2GHz. By comparison, the 130nm 970, currently used by Apple in its Power Mac G5 desktop line, consumes 51W at 1.8GHz.
Youd expect the smaller process to yield a power reduction at close clock speeds, but the issue of current leakage at the smaller transistor size can counter that assumption. Certainly thats what Intel has been forced to accept - Prescott consumes more power clock-for-clock than its 130nm predecessor, "Northwood". One crucial difference between IBMs processors and Intels is the formers use of silicon-on-insulator technology, which undoubtedly helps reduce leakage at the smaller process. That bodes well for AMD. Its 90nm processors are due later this year. Like the IBM chips, they too utilise SOI. IBMs success lends weight to the claim by American Technology Research analyst Rick Whittington that SOI will be crucial to AMDs transition to 90nm.
News source: The Register