PowerMac G4 Upgrades

Configuration

This is one of the first PowerMac G4 machines, with the new PowerPC G4 7400 processor and AGP 2x, nickname "Sawtooth" released in 1999.

This machine works as a Xerox printer rip and workstation, featuring dual Xerox 64-bit PCI printer controller cards. As this is a production machine every upgrade has to be thoroughly tested and easy to replace if an issue crops up. The Xerox Splash printer server software is only available for Mac OS 9.

Original

• PowerPC Single 450MHz G4 7400 w/1MB SDR L2 cache
• 100MHz SDR bus w/1GB RAM
• OEM Western Digital 20 GB hard drive
• Onboard ATA/66 hard drive controller
• OEM Pioneer DVR-103 Superdrive
• OEM ATI Rage 120 Pro AGP 16MB graphics card
• Expansion Slots: 3 64-bit 33 MHz PCI, 1 2x AGP
• Mac OS 9.0.4

Upgraded

As of May 2008.

• 2x 256MB 1x 512MB, total 1 GB 100 MHz RAM
• New exhaust fan
• New graphics card fan
• 2x Seagate 80GB 7200 RPM hard drives - SoftRaid Raid0
• External Western Digital USB/Firewire backup hard drive
• Pioneer DVR-112 16x Superdrive
• Mac OS 9.2.2

CPU Upgrade

There are several CPU upgrades available for the PowerMac G4 line. The CPU die is located on a daughterboard and socketed onto the motherboard, fastened with 3 screws. Upgrading the CPU requires only removal of the heatsink and the screws.

PowerPC G4

The PowerPC G4 microprocessor was a collaboration between Apple, IBM, and Motorola (Freescale). During its lifespan it evolved from clock speeds ranging from 350 MHz up to 2.0 GHz (overclocked 1.6GHz).

• PowerPC 7400 - 1MB L2 - 200nm
• PowerPC 7410 - 1MB L2 - 180nm
• PowerPC 7450 - 256KB L2 - 2MB L3 cache - 180nm
• PowerPC 7445 - 256KB L2 - 180nm
• PowerPC 7455 - 256KB L2 - 2MB L3 cache - 180nm
• PowerPC 7447 - 512KB L2 - 130nm
• PowerPC 7457 - 512KB L2 - 2MB L3 cache - 130nm
• PowerPC 7448 - 1MB L2 - 90nm

For more details, see the PowerPC G4 article on Wikipedia.

Manufacturers

There are several manufacturer of CPU upgrade boards for the PowerMac.

• Other World Computing (OWC)
• Sonnet Tech
• Newer Technology
• Giga Designs - Out of business?

Upgrade boards

All the latest upgrades based on 7447, 7457, 7457, and 7448 all require an initial firmware patch by holding the programmer button and boot a CD to patch the NVRAM. The patch includes 7457/7447A/7448 enabler patch, PLL patch for correct System Profiler speed report, L3CR extended ratios patch to correct L3 cache ratio above 6:1, and thernal fan control [1]. Also the CPU Plugins extensions has to be disabled in the Extensions folder or on any boot CDs, or else the machine will freeze before the desktop loads.

Fortunately, boards based on 7455 does not require any patching or special handling, and can be used as a straight drop-in replacement.

7448 vs 7455 performance

The latest 7447/7448 processors doesn't include a L3 interface, only the slightly older 7455/7457 has a 2MB L3 cache. Benchmarks shows that a 7455 1.42 GHz can outperform or equal a 7448 1.8 GHz on numerous tests almost solely because of the extra L3 cache, especially earlier machines that has slow bus/memory speed and with throughput intensive applications (e.g. Sawtooth and Photoshop) can get an advantage of the L3 cache. Althought the 7455 is older and runs hotter because of the 180 nm vs 130 nm manufacturer process, the 7455 based CPU upgrades usually sells for much less than the newer 7448 boards.

• BareFeats MAXPower 7448 vs 7447 vs 7455 vs Core Duo benchmark
• xlr8yourmac PowerLogix 7447A vs 7457 benchmark
• Sonnet 1.7 GHz 7447 vs OWC 1.467 GHz 7455
• Xbench PowerMac G4 AGP chart

Upgrade candidates

This Sawtooth G4 has has several key limitations and requirements that has to be taken into consideration before an CPU upgrade:

• 100 MHz system bus
• Uni-North (Uni-N) ASIC bridge chip revision: 3 (dual processors require revision 7 or later, found March 2000 and later)
• Firmware 4.2.8 (latest)
• Production workstation

These candidates were available as of May 2008:

1. OWC Mercury Extreme G4/1.467GHz-1.5GHz 7455B 256KB 1:1 L2 cache - 2MB SDR 233 MHz 6:1 L3 cache - manual - no patch or extension removal needed - $260
2. FastMac 1.467-1.5 GHz 7455 - 256K 1:1 L2 cache - 2MB SDR L3 cache - [http://fastmac.com/downloads/newagpinstall.pdf manual - no patch or extension removal needed - $260
3. NewerTech MAXPower G4/7448 1.8 GHz 7448 1MB 1:1 L2 cache - manual- $340
4. Sonnet Encore/ST G4 1.8 GHz 7448 512KB 1:1 L2 cache - $270

The OWC Mercury tops the list because of the easy installation without the need to patch and remove extensions, L3 cache advantage on Macs with slower bus speed vs higher clock speed, great performance-to-price ratio, clean install fan plugs onto board, and great OWC reputation and support.

Dual processors upgrades are out because of the incompatible Uni-North bridge chip.

Software

These utilities lets you view system details and sometimes configure the CPU upgrade (manufacturer dependant).

• Sonnet Metronome 3.0 | 2.3
• Powerlogix CPU Director 2.3b4 (OS9, 10.3) | 2.3b6 (10.5) - Preview
• NewerTech Gauge Pro 1.0.2 | 1.1

References

• PowerPC G4 processor evolution article
• PowerLogix 7447A and 7457 CPU upgrade benchmarks
• xlr8yourmac PowerMac G4 AGP CPU upgrade survey
• PowerLogix SRD vs DDR L3 cache whitepaper
• PowerMac G4 upgrade information
• Engadget how to upgrade G4 processor
• OWC Mercury CPU upgrade pictures and manual
• First generation OWC Mercury 1.467 GHz 7455 CPU upgrade review
• NewerTech 7448 installation manual
• BareFeats 7448 vs 7455 benchmarks
• Sonnet 1.7 GHz 7447 vs OWC Mercury 1.467 GHz 7455 benchmark picture
• PowerMac G4 vs OWC Mercury CPU upgrade benchmarks - bottom