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Review: MAChCarrier^TM G3/500 CPU Card
10X G3 CPU Upgrade for PCI Macs
Published: 11/02/99

Software Cache Control Features

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

Cache Control Software

XLR8 has updated their Cache Control software since my first CarrierZIF review , adding the capability to disable motherboard cache (my only complaint with the earlier version). Previously only Newer Technology's G3 cache control had this capability but now XLR8 and Powerlogix's do as well. This is a nice feature for owners of soldered-in cache on Macs like the 9500, some 9600 and Umax models. Motherboard cache is often the cause of both stability problems and bus speed limits with many G3 CPU upgrades. I still have my doubts that software cache disabling can prevent some cold startup problems with too-slow motherboard cache, so if possible, I still recommend removing the motherboard cache before installing a G3 CPU card if your Mac has a cache dimm. Slow L2 cache dimms are the #1 cause of CPU upgrade problems.
The XLR8 cache control features automatic cache speed testing (which can be a bit optimistic as I'll explain later), 'Virtual Firmware' to address compatibility issues with older Mac ROMs and an option to disable 'Speculative Processing' of the G3 which can cause problems with some applications like Retrospect backup software. "Speculative Processing" is often called code 'Branch Prediction' where the CPU makes educated guesses on future code execution. See XLR8's white paper for more details.

What's On The CD:

The XLR8 CD contains installers for all of the CPU upgrades and also features additional software such as the Power Pack (Fractal program and excellent Power Control utility that can perform system tests on the CPU, RAM, and SCSI devices. PowerControl can also report RAM configuration (interleaving status and installed dimm sizes) and much more. It's a great bonus and its RAM test has detected suspect DIMMs in where other free utilities didn't in my experience.

For those of you that have never used it, I highly recommend you read my Power Control page for a summary of what this utility can do.

Installing the Software:

XLR8 recommends installing their software before installing the card. Earlier versions of the installer required a 604 CPU or better to run (noted by some 7500 owners) but this has been revised so now so even owners of 601 CPUs will be able to install the software before replacing their existing card.

The XLR8 software installer automatically places the cache control and extension in the system folder. By having the control software already installed when you first boot with the G3 upgrade their 'virtual firmware' ensures that any compatibility issues such as the Adaptec wide SCSI cards are solved.

During the first boot with the G3 card (or whenever you change speed settings on the card), the XLR8 software tests the backside cache automatically and reports what it suggests is the maximum reliable cache speed (but offering you the option to manually set the speed to another setting). Regardless of suggested speeds from this test, I highly recommend keeping the cache at 1/2 the CPU speed or near the cache rating. Most cache used on today's upgrades cannot run reliably at speeds near 300MHz and cache speed is not a major factor in real-world application performance (CPU speed is).

I kept the review's card backside cache at a 2:1 ratio (half the CPU speed) throughout my tests. This particular card ran perfectly at speeds of up to 262.9Mhz with this particular 500/250 rated sample (results with another cards may vary). Again, backside cache speed is not a primary factor in real world applications performance so don't push the bleeding edge on cache speed as it can affect reliability.

MacBench's CPU test is highly influenced by cache speeds, but real world applications are far less so. Remember - a fast unreliable computer is far less useful (and hazardous to your data) than a slow reliable one. Don't sacrifice reliability for a few % faster CPU or Cache speeds. It's just plain foolish.

XLR8 Cache Control 1.41 Settings Page

MAChCarrier G3/500 in Genesis w/Default settings
(for 9600/350 report click here)

Maximum Reliable Speeds in both 9600 and Genesis:
525.8/262.9/52.6 (NOT RECOMMENDED)

The main page of the control panel lists the amount of installed RAM and system bus speed, CPU type, speed and CPU junction (internal) temperature.

About Reported Temperatures: Although the 40-44C temperatures indicated with this card are closer to what I'd expect, as I've mentioned many times in the past in the front page news, and in the CPU ratings database; in many cases I don't believe the reported temperatures are accurate (especially with copper CPUs - get our exclusive PPC Checker to see if your G3 is copper based). Since the software just reads a register on the CPU unless a company performs extensive tests and applies a 'calibration factor' to the reading the temperatures are of little use in my opinion. (Note: most G3 desktop CPUs are rated for 65C junction temperatures.

Advanced Settings Page: The image below shows the 'Advanced' settings tab of the control.

Advanced Settings Tab

The Advanced settings page will allow you to set the backside cache speed to manual (you select a speed) or automatic (the default based on the card type and bootup testing). At cache speeds above 250MHz, the new 'write-through' cache setting becomes enabled as a safety precaution, since the faster copy-back (default mode) may not be reliable. In both the Genesis and 9600/350, I was able to uncheck this and run copy-back mode at cache speeds of 262.9 MHz (when testing at CPU speeds of 525.8MHz (525.8/262/9/52.6). Results in a different Mac with another sample may not be reliable at these speeds however.

Copy-Back (default) vs Write-Through Cache Modes: The default 'copy-back' cache mode is faster as writes are written to the backside cache (and later copied back to RAM if data has been changed). Write-through mode means that each CPU write is written directly to much slower main system RAM. Interesting is that the B&W G3s are set for write-through modes, but with their faster 100MHz memory bus speeds it's less of a performance issue than with older macs with much slower memory bus speeds. The 'Write-Through' option only becomes visible at cache speeds of over 250MHz (i.e. - when running at CPU speeds of over 500MHz). Although I do not recommended it to others, I was able to uncheck Write-Through mode and still run reliably at the maximum speed this CPU card in these systems would run - 525.8/262.9/52.6. I saw no errors in extensive tests at this speed, but these results may not be repeatable and are not recommended to others. Overclocking may void your warranty and lead to data loss and/or affect hardware reliability.

Speculative Processing:

There is also an option to enable or disable (default) Speculative Processing of the G3 CPU. Speculative Processing is often called 'branch prediction' - where the CPU tries to predict the execution paths of the program code. As noted previously, older Macs do not have 'G3-Clean' ROMs so it is advised to keep Speculative Processing disabled (required for software like Retrospect Backup to work 100% reliably). There is a small (4% or so) performance hit in many applications with Spec. Processing disabled, but Photoshop 5 tests actually showed higher filter performance with it disabled in my tests.

Motherboard Cache Enable/Disable:

Version v1.4 and later of the control added an option to disable (the default setting) any motherboard cache, which as I mention earlier is a nice feature for owners of soldered-in cache motherboard designs like the 9500, some 9600s and Umax machines. If possible however remove any L2 cache dimms on your motherboard before installing any G3 upgrade card. This helps prevent the #1 cause of startup or stability problems with G3 CPU upgrades. The motherboard L2 cache is of no real benefit with a G3 CPU card that has its own much faster (and often larger) backside L2 cache on the card.

The 'Performance Tips' tab contains notes on faster cache speed settings and tuning. The 'Support' tab lists XLR8's contact information including toll-free tech support line and web site address (a nice feature).

Summary: Software controls were easy to install, use and contained options to enhance compatibility and performance. Overall I consider XLR8's cache control the best I've seen so far.

The next page describes the documentation and installation instructions supplied with the card. Or you may use the links below to jump to a specific page.

Index of XLR8 MAChCarrier G3/500 Review Pages
Intro | Benchmarks | Appl. Tests | Software Controls | Docs/Installation | Specs/Design | Summary

- or -
Back to WWW.XLR8YOURMAC.COM

Copyright © Mike, 1999.
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: MAChCarrier^TM G3/500 CPU Card 10X G3 CPU Upgrade for PCI Macs Published: 11/02/99
Software Cache Control Features
Intro \| Benchmarks \| Appl. Tests \| Software Controls \| Docs/Installation \| Specs/Design \| Summary
Cache Control Software
XLR8 has updated their Cache Control software since my first CarrierZIF review , adding the capability to disable motherboard cache (my only complaint with the earlier version). Previously only Newer Technology's G3 cache control had this capability but now XLR8 and Powerlogix's do as well. This is a nice feature for owners of soldered-in cache on Macs like the 9500, some 9600 and Umax models. Motherboard cache is often the cause of both stability problems and bus speed limits with many G3 CPU upgrades. I still have my doubts that software cache disabling can prevent some cold startup problems with too-slow motherboard cache, so if possible, I still recommend removing the motherboard cache before installing a G3 CPU card if your Mac has a cache dimm. Slow L2 cache dimms are the #1 cause of CPU upgrade problems. The XLR8 cache control features automatic cache speed testing (which can be a bit optimistic as I'll explain later), 'Virtual Firmware' to address compatibility issues with older Mac ROMs and an option to disable 'Speculative Processing' of the G3 which can cause problems with some applications like Retrospect backup software. "Speculative Processing" is often called code 'Branch Prediction' where the CPU makes educated guesses on future code execution. See XLR8's white paper for more details. What's On The CD: The XLR8 CD contains installers for all of the CPU upgrades and also features additional software such as the Power Pack (Fractal program and excellent Power Control utility that can perform system tests on the CPU, RAM, and SCSI devices. PowerControl can also report RAM configuration (interleaving status and installed dimm sizes) and much more. It's a great bonus and its RAM test has detected suspect DIMMs in where other free utilities didn't in my experience. For those of you that have never used it, I highly recommend you read my Power Control page for a summary of what this utility can do. Installing the Software: XLR8 recommends installing their software before installing the card. Earlier versions of the installer required a 604 CPU or better to run (noted by some 7500 owners) but this has been revised so now so even owners of 601 CPUs will be able to install the software before replacing their existing card. The XLR8 software installer automatically places the cache control and extension in the system folder. By having the control software already installed when you first boot with the G3 upgrade their 'virtual firmware' ensures that any compatibility issues such as the Adaptec wide SCSI cards are solved. During the first boot with the G3 card (or whenever you change speed settings on the card), the XLR8 software tests the backside cache automatically and reports what it suggests is the maximum reliable cache speed (but offering you the option to manually set the speed to another setting). Regardless of suggested speeds from this test, I highly recommend keeping the cache at 1/2 the CPU speed or near the cache rating. Most cache used on today's upgrades cannot run reliably at speeds near 300MHz and cache speed is not a major factor in real-world application performance (CPU speed is). I kept the review's card backside cache at a 2:1 ratio (half the CPU speed) throughout my tests. This particular card ran perfectly at speeds of up to 262.9Mhz with this particular 500/250 rated sample (results with another cards may vary). Again, backside cache speed is not a primary factor in real world applications performance so don't push the bleeding edge on cache speed as it can affect reliability. MacBench's CPU test is highly influenced by cache speeds, but real world applications are far less so. Remember - a fast unreliable computer is far less useful (and hazardous to your data) than a slow reliable one. Don't sacrifice reliability for a few % faster CPU or Cache speeds. It's just plain foolish. XLR8 Cache Control 1.41 Settings Page MAChCarrier G3/500 in Genesis w/Default settings (for 9600/350 report click here) Maximum Reliable Speeds in both 9600 and Genesis: 525.8/262.9/52.6 (NOT RECOMMENDED) The main page of the control panel lists the amount of installed RAM and system bus speed, CPU type, speed and CPU junction (internal) temperature. About Reported Temperatures: Although the 40-44C temperatures indicated with this card are closer to what I'd expect, as I've mentioned many times in the past in the front page news, and in the CPU ratings database; in many cases I don't believe the reported temperatures are accurate (especially with copper CPUs - get our exclusive PPC Checker to see if your G3 is copper based). Since the software just reads a register on the CPU unless a company performs extensive tests and applies a 'calibration factor' to the reading the temperatures are of little use in my opinion. (Note: most G3 desktop CPUs are rated for 65C junction temperatures. Advanced Settings Page: The image below shows the 'Advanced' settings tab of the control. Advanced Settings Tab The Advanced settings page will allow you to set the backside cache speed to manual (you select a speed) or automatic (the default based on the card type and bootup testing). At cache speeds above 250MHz, the new 'write-through' cache setting becomes enabled as a safety precaution, since the faster copy-back (default mode) may not be reliable. In both the Genesis and 9600/350, I was able to uncheck this and run copy-back mode at cache speeds of 262.9 MHz (when testing at CPU speeds of 525.8MHz (525.8/262/9/52.6). Results in a different Mac with another sample may not be reliable at these speeds however. Copy-Back (default) vs Write-Through Cache Modes: The default 'copy-back' cache mode is faster as writes are written to the backside cache (and later copied back to RAM if data has been changed). Write-through mode means that each CPU write is written directly to much slower main system RAM. Interesting is that the B&W G3s are set for write-through modes, but with their faster 100MHz memory bus speeds it's less of a performance issue than with older macs with much slower memory bus speeds. The 'Write-Through' option only becomes visible at cache speeds of over 250MHz (i.e. - when running at CPU speeds of over 500MHz). Although I do not recommended it to others, I was able to uncheck Write-Through mode and still run reliably at the maximum speed this CPU card in these systems would run - 525.8/262.9/52.6. I saw no errors in extensive tests at this speed, but these results may not be repeatable and are not recommended to others. Overclocking may void your warranty and lead to data loss and/or affect hardware reliability. Speculative Processing: There is also an option to enable or disable (default) Speculative Processing of the G3 CPU. Speculative Processing is often called 'branch prediction' - where the CPU tries to predict the execution paths of the program code. As noted previously, older Macs do not have 'G3-Clean' ROMs so it is advised to keep Speculative Processing disabled (required for software like Retrospect Backup to work 100% reliably). There is a small (4% or so) performance hit in many applications with Spec. Processing disabled, but Photoshop 5 tests actually showed higher filter performance with it disabled in my tests. Motherboard Cache Enable/Disable: Version v1.4 and later of the control added an option to disable (the default setting) any motherboard cache, which as I mention earlier is a nice feature for owners of soldered-in cache motherboard designs like the 9500, some 9600s and Umax machines. If possible however remove any L2 cache dimms on your motherboard before installing any G3 upgrade card. This helps prevent the #1 cause of startup or stability problems with G3 CPU upgrades. The motherboard L2 cache is of no real benefit with a G3 CPU card that has its own much faster (and often larger) backside L2 cache on the card. The 'Performance Tips' tab contains notes on faster cache speed settings and tuning. The 'Support' tab lists XLR8's contact information including toll-free tech support line and web site address (a nice feature).
Summary: Software controls were easy to install, use and contained options to enhance compatibility and performance. Overall I consider XLR8's cache control the best I've seen so far.
The next page describes the documentation and installation instructions supplied with the card. Or you may use the links below to jump to a specific page.

Index of XLR8 MAChCarrier G3/500 Review Pages Intro \| Benchmarks \| Appl. Tests \| Software Controls \| Docs/Installation \| Specs/Design \| Summary - or - Back to WWW.XLR8YOURMAC.COM
Copyright © Mike, 1999. 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.