Specifications

Power Mac G5 (Late 2004) Basics - 4
What’s New
PowerPC G5 Processor
The processor used in the Power Mac G5 (Late 2004) has the following features:
• Single 1.8 GHZ processor
• 64-bit PowerPC implementation with 42-bit physical memory addressing
• Core runs at three times the bus speed
• Superscalar execution core supporting more than 200 in-flight instructions
• Two independent double-precision floating point units
• Velocity Engine: 128-bit-wide vector execution unit
• 64K L1 instruction cache, 32K L1 data cache per processor
• Built-in 512 KB backside L2 cache per processor
• Two independent, unidirectional 600 MHz frontside buses supporting 4.8 GBps data
throughput
System Management Unit (SMU)
The advanced system management unit of the Power Mac G5 (Late 2004) employs
advanced thermal and wattage management to keep acoustic noise of the fans to a
minimum. The enclosure is divided into discrete zones, each with independently controlled
fans bringing in cool air from the front of the enclosure, directing it over system
components and exhausting it out the rear. Temperature and power consumption are
monitored by the operating system, which communicates with the SMU, which in turn
controls and monitors fan operation. Note that if Mac OS X is not booted, thermal
management must be provided by the alternate development operating system.
The SMU monitors the wattage from 0 to 100 W. The fan speeds are increased
proportionally, where 100 W operates the fans at highest speed. The wattage calculation
does not include the 25 V ADC power output.