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IBM claims massive power cut for 90nm G5

Good news for AMD - but not Intel

You can see why Apple waited for the 90nm version of the PowerPC 970 before launching a G5-based Xserve 1U rackmount server: the latter's heat dissipation characteristics.

While Intel continues to have problems with the power consumed by its 90nm 'Prescott' processor - 100W at around 3.2GHz - IBM's 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.

You'd 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 that's what Intel has been forced to accept - Prescott consumes more power clock-for-clock than its 130nm predecessor, 'Northwood'.

One crucial difference between IBM's processors and Intel's is the former's 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. IBM's success lends weight to the claim by American Technology Research analyst Rick Whittington that SOI will be crucial to AMD's transition to 90nm.

The 970FX, meanwhile, consumes a mere 12.3W at 1.4GHz, paving the way for PowerBook G5s. That figure is comparable to the 7.5W a 1GHz consumption of the G4-class Motorola MPC7447 that drives the current PowerBook G4s. The 970FX's SpeedStep-style PowerTune technology will help too. It also lays the foundation for faster desktops, including the 3GHz version Apple CEO Steve Jobs has promised for next summer.

IBM is expected to offer more details of the 970 at the IEEE Solid State Circuits Conference next month. For now, the name and power characteristics are all we know, coming from the company's latest processor Quick Reference Guide. ®

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