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Review: PowerForce G4 350MHz
G4 CPU Upgrade for PCI Macs
By Mike
Published: 1/23/2000

Hardware Features/Specifications/Compatibility

Intro | Benchmarks | Appl. Tests | Software Controls | Installation | Specs/Design | Summary

PowerForce G4 350 Technical Details

.

Hardware Details:

Motorola 350MHz PowerPC 7400 (G4) CPU v2.2 (later samples may vary)
1MB of Sync. Pipeline Burst SRAM L2 Cache
Samsung KM736V799T-44 (4.4ns cycle time) x 2
(225 MHz rated)

3 year limited warranty (per Rev A manual)

Speed Settings Range:
The Powerforce G4, like all their new small card designs has the following range of bus speeds and bus/cpu ratios, selectable via an on-card series of switches:

Bus Speeds:

40.0 MHz
42.5 MHz
45.0 MHz
46.6 MHz
50.0 MHz (default as shipped)
52.5 MHz
55 MHz
60 MHz

Several readers have misread the manual's switch settings, reading the down lever position as up even though the manual illustrations are correct and clear to me. If you're unclear on the switch settings, Powerlogix has posted a downloadable switch demo. For reasons why Powerlogix offer adjustable bus speeds , see http://www.powerlogix.com/support/bus.html.
Bus/CPU Ratios:

4:1 to 10:1 (7x set as default for this model)

Although the card allows setting other ratios since it was designed to use a G3 CPU with optional 10X ratio, the G4 CPU only supports a maximum 9:1 bus/cpu ratio setting in the current revision . Also note the lower ratios are not really of any use as they would severely underclock the CPU.
(Remember the formula of Bus speed x ratio = CPU speed.)

Overclocking, although very common and something I have personally done for many years on literally every computer I have ever owned without any failures so far, is not recommended as may not be reliable and could cause a loss of data or premature hardware failure. (Powerlogix's current FAQ notes they honor the warranty on the card regardless of speeds run, however the warranty does not extend to your data or other than the CPU card.)
Speed is nothing without reliability and you risk your data and hardware when overclocking. Often I see folks run the ragged edge of stability, which leaves no margin for increased temperatures, timing, etc. Often pushing for that last 5% increase in clock speed ruins the systems's stability. (And realize a 5-10% increase in clock speed won't provide a 'noticable' gain in performance).
See my FAQ's Overclocking Risks topic area for more information, including long term effects such as electromigration. Along with the freedom to change settings, adjustable cards also carry the potential for setting speeds that will not run reliably. It's your responsibility to verify your settings are reliable should you decide to risk running speeds other than the default (rated) speeds.

Powerlogix, like all G3/G4 manufacturers other than Newer Technology, relies on software to address the issues of Speculative Access in older Macs. PowerLogix responses to this issue can be found at http://www.powerlogix.com/support/spec.html. The Software controls page of this review cover this issue in more detail.

System Compatibility:

The PowerForce G4 is listed as compatible with the following Mac models:

Apple PowerMac 7300, 7500, 7600, 8500, 8600, 9500 & 9600
Umax S900 and J700
PowerComputing PowerBase, PowerWave, PowerTower Pro (but not the PowerTower)
Daystar Genesis/Millennium

Currently the PowerForce G4 is the only G4 CPU upgrade compatible with the PowerBase. Note that unlike G3 CPU upgrades, no current G4 upgrade is compatible with Catalyst motherboard based Macs like the PowerCenter/PowerCenter Pro and PowerTower models. (PowerTower Pro models are based on a different motherboard and are listed as compatible.) To verify the latest compatibility information for all of Powerlogix's CPU upgrades, see the compatibility matrix Powerlogix web site.

Test System Hardware Summary

Apple PowerMac 9600/350

320MB Interleaved RAM
ATTO ExpressPCI Ultra2 SCSI card
Seagate Cheetah 4.5GB U2 SCSI drive (used for all tests)
Stock 4GB SCSI hard drive (5400 rpm, 512KB cache)
[This drive conained OS 8.1 and was not used in tests for this review]
Apple 24x CDROM drive (OEM)
OEM SCSI ZIP drive
ATI Rage128 OEM rev1 graphics card (from B&W G3 rev 1)
(this card has a slower clock speed than rev 2 or retail Rage128 versions)
All OS 9 Altivec extensions were enabled for G4 CPU tests
OS 9.0, VM off, QT 4.0.3, QD3D 1.6., OpenGL 1.1.2, [No Libmoto]
Dual 3Dfx Voodoo2 PCI cards (used for Unreal game tests in SLI mode)

Card Design Summary:

The review sample ran reliably in my 9600/350, even at speeds above the CPU's ratings (400MHz tested with this 350MHz rated sample). Since this upgrade card is a relatively new design with a different clock circuit, board layout and components (such as voltage regulation), it's too early to tell what the long term reliability will be. However Powerlogix warrants the card with a 3 year limited warranty, regardless of speed settings used.

For other owner reports on this upgrade, search my Rate Your CPU Upgrade using Powerlogix G4 as the upgrade card brand. (You can also limit searches further by selecting your specific Mac model/series, although the PF G4 is too new to have very many owner reports to date.) If you are an owner of this upgrade, please submit your comments and ratings on this upgrade (after you've ran the upgrade for at least several weeks).

My only problems seen during testing in the 9600/350 were solved by moving the Atto PCI Ultra2 SCSI card to slot 3 for reliable operation of Virtual PC 3.0, SoundJam MP, and OpenGL games (the latter two issues were common with other brands of G4 cards as well until the SCSI card was moved to the upper PCI slots).
As with every brand of G4 upgrade I've tried so far (XLR8, PowerLogix, Newer Tech), my Genesis with Softraid 2.2.1 disk drivers would not run any G4 card reliably (although G3 upgrades run fine). I suspect if the hard drives had Apple's OS 9 drivers, or perhaps disabling Softraid's driver acceleration (a unique feature) this may have solved the problem. I intend on testing this in my review of the PowerForce G4/400 card. Based on experience so far, I'm still less confortable recommending G4 upgrades for older Macs with lots of hardware (PCI Cards) installed. G4 upgrade card hardware and software is too new for me to have a good feeling about long term stability and possible hardware/software compatibility issues.

The next page contains a summary and final comments on the product.

Index of PowerForce G4 350MHz Review
Intro | Benchmarks | Appl. Tests | Software Controls | Installation | Specs/Design | Summary

- or -
Back to WWW.XLR8YOURMAC.COM

Copyright © Mike, 2000.
All Rights Reserved.
All brand or product names mentioned here are properties of their respective companies.

Users of the web site must read and are bound by the terms and conditions of use.

The Source for Mac Performance News and Reviews
Review: PowerForce G4 350MHz G4 CPU Upgrade for PCI Macs By Mike Published: 1/23/2000
Hardware Features/Specifications/Compatibility
Intro \| Benchmarks \| Appl. Tests \| Software Controls \| Installation \| Specs/Design \| Summary
PowerForce G4 350 Technical Details
. Hardware Details: Motorola 350MHz PowerPC 7400 (G4) CPU v2.2 (later samples may vary) 1MB of Sync. Pipeline Burst SRAM L2 Cache Samsung KM736V799T-44 (4.4ns cycle time) x 2 (225 MHz rated) 3 year limited warranty (per Rev A manual) Speed Settings Range: The Powerforce G4, like all their new small card designs has the following range of bus speeds and bus/cpu ratios, selectable via an on-card series of switches: Bus Speeds: 40.0 MHz 42.5 MHz 45.0 MHz 46.6 MHz 50.0 MHz (default as shipped) 52.5 MHz 55 MHz 60 MHz Several readers have misread the manual's switch settings, reading the down lever position as up even though the manual illustrations are correct and clear to me. If you're unclear on the switch settings, Powerlogix has posted a downloadable switch demo. For reasons why Powerlogix offer adjustable bus speeds , see http://www.powerlogix.com/support/bus.html. Bus/CPU Ratios: 4:1 to 10:1 (7x set as default for this model) Although the card allows setting other ratios since it was designed to use a G3 CPU with optional 10X ratio, the G4 CPU only supports a maximum 9:1 bus/cpu ratio setting in the current revision . Also note the lower ratios are not really of any use as they would severely underclock the CPU. (Remember the formula of Bus speed x ratio = CPU speed.) Overclocking, although very common and something I have personally done for many years on literally every computer I have ever owned without any failures so far, is not recommended as may not be reliable and could cause a loss of data or premature hardware failure. (Powerlogix's current FAQ notes they honor the warranty on the card regardless of speeds run, however the warranty does not extend to your data or other than the CPU card.) Speed is nothing without reliability and you risk your data and hardware when overclocking. Often I see folks run the ragged edge of stability, which leaves no margin for increased temperatures, timing, etc. Often pushing for that last 5% increase in clock speed ruins the systems's stability. (And realize a 5-10% increase in clock speed won't provide a 'noticable' gain in performance). See my FAQ's Overclocking Risks topic area for more information, including long term effects such as electromigration. Along with the freedom to change settings, adjustable cards also carry the potential for setting speeds that will not run reliably. It's your responsibility to verify your settings are reliable should you decide to risk running speeds other than the default (rated) speeds. Powerlogix, like all G3/G4 manufacturers other than Newer Technology, relies on software to address the issues of Speculative Access in older Macs. PowerLogix responses to this issue can be found at http://www.powerlogix.com/support/spec.html. The Software controls page of this review cover this issue in more detail. System Compatibility: The PowerForce G4 is listed as compatible with the following Mac models: Apple PowerMac 7300, 7500, 7600, 8500, 8600, 9500 & 9600 Umax S900 and J700 PowerComputing PowerBase, PowerWave, PowerTower Pro (but not the PowerTower) Daystar Genesis/Millennium Currently the PowerForce G4 is the only G4 CPU upgrade compatible with the PowerBase. Note that unlike G3 CPU upgrades, no current G4 upgrade is compatible with Catalyst motherboard based Macs like the PowerCenter/PowerCenter Pro and PowerTower models. (PowerTower Pro models are based on a different motherboard and are listed as compatible.) To verify the latest compatibility information for all of Powerlogix's CPU upgrades, see the compatibility matrix Powerlogix web site. Test System Hardware Summary Apple PowerMac 9600/350 320MB Interleaved RAM ATTO ExpressPCI Ultra2 SCSI card Seagate Cheetah 4.5GB U2 SCSI drive (used for all tests) Stock 4GB SCSI hard drive (5400 rpm, 512KB cache) [This drive conained OS 8.1 and was not used in tests for this review] Apple 24x CDROM drive (OEM) OEM SCSI ZIP drive ATI Rage128 OEM rev1 graphics card (from B&W G3 rev 1) (this card has a slower clock speed than rev 2 or retail Rage128 versions) All OS 9 Altivec extensions were enabled for G4 CPU tests OS 9.0, VM off, QT 4.0.3, QD3D 1.6., OpenGL 1.1.2, [No Libmoto] Dual 3Dfx Voodoo2 PCI cards (used for Unreal game tests in SLI mode)
Card Design Summary: The review sample ran reliably in my 9600/350, even at speeds above the CPU's ratings (400MHz tested with this 350MHz rated sample). Since this upgrade card is a relatively new design with a different clock circuit, board layout and components (such as voltage regulation), it's too early to tell what the long term reliability will be. However Powerlogix warrants the card with a 3 year limited warranty, regardless of speed settings used. For other owner reports on this upgrade, search my Rate Your CPU Upgrade using Powerlogix G4 as the upgrade card brand. (You can also limit searches further by selecting your specific Mac model/series, although the PF G4 is too new to have very many owner reports to date.) If you are an owner of this upgrade, please submit your comments and ratings on this upgrade (after you've ran the upgrade for at least several weeks). My only problems seen during testing in the 9600/350 were solved by moving the Atto PCI Ultra2 SCSI card to slot 3 for reliable operation of Virtual PC 3.0, SoundJam MP, and OpenGL games (the latter two issues were common with other brands of G4 cards as well until the SCSI card was moved to the upper PCI slots). As with every brand of G4 upgrade I've tried so far (XLR8, PowerLogix, Newer Tech), my Genesis with Softraid 2.2.1 disk drivers would not run any G4 card reliably (although G3 upgrades run fine). I suspect if the hard drives had Apple's OS 9 drivers, or perhaps disabling Softraid's driver acceleration (a unique feature) this may have solved the problem. I intend on testing this in my review of the PowerForce G4/400 card. Based on experience so far, I'm still less confortable recommending G4 upgrades for older Macs with lots of hardware (PCI Cards) installed. G4 upgrade card hardware and software is too new for me to have a good feeling about long term stability and possible hardware/software compatibility issues.
The next page contains a summary and final comments on the product.

Index of PowerForce G4 350MHz Review Intro \| Benchmarks \| Appl. Tests \| Software Controls \| Installation \| Specs/Design \| Summary - or - Back to WWW.XLR8YOURMAC.COM
Copyright © Mike, 2000. All Rights Reserved. All brand or product names mentioned here are properties of their respective companies. Users of the web site must read and are bound by the terms and conditions of use.