Power Measurement on the Apple Power Mac G5

This report describes the instrumentation developed for the dynamic measurement of power and temperature for the Apple Power Mac G5. The G5 employs one or two 64-bit PowerPC 970 processors and runs Mac OS X, and 32-bit or 64-bit Linux. Apple has implemented a set of temperature, power and fan RPM sensors. OS X uses the sensors for fan speed control, in order to minimize the acoustic disturbance of a deskside system. The following metrics are obtained.
• Fans rpm
• Fans outlet temperatures
• Voltage to each 970 processor
• Current to each 970 processor
• Temperature of each 970 processor
Note: This report describes the first revision of the dual-processor 2.0 GHz Power Mac G5. By the time you read this, a newer liquid-cooled dual-processor 2.5 GHz model will be available.

By: Wes Felter, Tom Keller

Published in: RC23276 in 2004


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