Accelerate Your Mac! - Review of the XLR8 MAChCarrier G4/450 CPU upgrade

The MAChCarrier folder contains the software controls for this card. The image below shows the contents of that folder:

The XLR8 CD contains installers for all of their 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 my experience which other free RAM test utilities didn't.

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 upgrade card in older Macs, which is a must with G4 upgrades in pre-Beige G3 systems due to issues of Speculative Processing with older ROM version Macs. (The exceptions are 8600/250, 8600/300, 9600/300 and 9600/350 Macs which usually have ROMs that are allow Speculative Processing to be enabled.)

The XLR8 software installer automatically places the cache control and extension in the system folder. During the first boot with the new CPU card (or if you change any speed settings on the card itself), 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 accept the default 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. 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 slower but reliable one. Don't sacrifice reliability for a few % faster CPU or Cache speeds. It's just plain foolish.

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:
The maximum 'reported' temperature seen in the S900 during testing was 56C. An overnight RAM test was run to ensure reliability in the S900 and that there were no memory errors with the installed RAM. As I've mentioned many times in the past in the front page news, and in the CPU ratings database; I don't believe the reported temperatures are always 100% accurate. (Some copper G3 CPU reports are often at or below room temperature, which is impossible with only a heatsink.) However the 55C reported for this CPU may be literally accurate. A G4/450 with a heatsink the size of this one will run hotter than most CPU upgrades. The Specs on the G4 show it dissipates quite a bit more heat (wattage) than a G3. Most desktop CPUs are rated for 65C max. operating temperature so 55C is well within the operating range. I do not recommend you run 450MHz G4 upgrades without the cover on the case which is requiired for proper airflow.

In very limited tests in my Beige G3 (removing the G4 ZIF from the Carrier card), I had a lockup in a long rendering test using the stock Beige G3 heatsink, perhaps thermal related but that is just a guess.

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

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). Again I suggest you do not run the cache at speeds of more than 1/2 the CPU speed, despite what the boot testing may suggest as reliable.

The Power Savings option is enabled by default and allows the CPU to go into low-power mode (perhaps even the L2 cache) during extended periods of idle time.

Copy-Back (default) vs Write-Through Cache Modes:
'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 rather than being buffered by the much faster cache. The cache control may default to enabling write-through mode at some cache speeds for stability, but I had no errors with this review sample with write-through mode disabled at cache speeds of 225MHz.

About Speculative Processing:
"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. The XLR8 v1.4.3 control panel detected the S900 had a 'non-G3 clean' ROM and would not allow Speculative Processing to be enabled as a safety feature. (G4 CPUs are reportedly will not boot in older Macs if Speculative Processing is enabled.) All G3 and G4 CPU upgrades other than Newer Technologies use some sort of 'Virtual Firmware to address this issue. Newer Tech uses a patented hardware fix (programmed Xlinx chip, at least on the original G3 cards.)

There is a small (4% or so) performance hit in many applications with Spec. Processing disabled. Some Photoshop 5 tests I ran in the past actually showed higher filter performance with it disabled. All

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).

Easter Egg:
Holding down the Option key when selecting the 'About' menu option (under the Apple menu) while the XLR8 control is active will show the G4 CPU revision as the last 3 digits of the '0x000..." number shown under the MACh Speed Control version number. This G4 upgrade as noted previously in the review is the latest (as of April 2000) v2.9 stepping.

The Source for Mac Performance News and Reviews
Review: XLR8's MAChCarrier^TM G4/450 By Mike Breeden Published: 4/7/2000
Software Cache Control Features
Intro \| Benchmarks \| Appl. Tests \| Software Controls \| Installation \| Specs/Design \| Summary
Cache Control Software
XLR8's control features automatic cache speed testing (which can be a bit optimistic as I'll explain later) and their software uses 'Virtual Firmware' to address compatibility issues with older 60x CPU based Mac ROMs. This is not an issue with Kansas motherboard Macs like the 8600/250 and up, 9600/300 and up models based on my previous review tests. XLR8's CD also includes an "Emergency Boot Disk" image should your motherboard battery fail or if the Novram was cleared. More info on the issue of Speculative Processing in older Macs is listed below. What's On The XLR8 Universal Installer CD: The MAChCarrier folder contains the software controls for this card. The image below shows the contents of that folder: The XLR8 CD contains installers for all of their 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 my experience which other free RAM test utilities didn't. 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 upgrade card in older Macs, which is a must with G4 upgrades in pre-Beige G3 systems due to issues of Speculative Processing with older ROM version Macs. (The exceptions are 8600/250, 8600/300, 9600/300 and 9600/350 Macs which usually have ROMs that are allow Speculative Processing to be enabled.) The XLR8 software installer automatically places the cache control and extension in the system folder. During the first boot with the new CPU card (or if you change any speed settings on the card itself), 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 accept the default 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. 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 slower but reliable one. Don't sacrifice reliability for a few % faster CPU or Cache speeds. It's just plain foolish. XLR8 Cache Control Settings Page MAChCarrier G4/450 Default settings 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: The maximum 'reported' temperature seen in the S900 during testing was 56C. An overnight RAM test was run to ensure reliability in the S900 and that there were no memory errors with the installed RAM. As I've mentioned many times in the past in the front page news, and in the CPU ratings database; I don't believe the reported temperatures are always 100% accurate. (Some copper G3 CPU reports are often at or below room temperature, which is impossible with only a heatsink.) However the 55C reported for this CPU may be literally accurate. A G4/450 with a heatsink the size of this one will run hotter than most CPU upgrades. The Specs on the G4 show it dissipates quite a bit more heat (wattage) than a G3. Most desktop CPUs are rated for 65C max. operating temperature so 55C is well within the operating range. I do not recommend you run 450MHz G4 upgrades without the cover on the case which is requiired for proper airflow. In very limited tests in my Beige G3 (removing the G4 ZIF from the Carrier card), I had a lockup in a long rendering test using the stock Beige G3 heatsink, perhaps thermal related but that is just a guess. 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). Again I suggest you do not run the cache at speeds of more than 1/2 the CPU speed, despite what the boot testing may suggest as reliable. The Power Savings option is enabled by default and allows the CPU to go into low-power mode (perhaps even the L2 cache) during extended periods of idle time. Copy-Back (default) vs Write-Through Cache Modes: '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 rather than being buffered by the much faster cache. The cache control may default to enabling write-through mode at some cache speeds for stability, but I had no errors with this review sample with write-through mode disabled at cache speeds of 225MHz. About Speculative Processing: "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. The XLR8 v1.4.3 control panel detected the S900 had a 'non-G3 clean' ROM and would not allow Speculative Processing to be enabled as a safety feature. (G4 CPUs are reportedly will not boot in older Macs if Speculative Processing is enabled.) All G3 and G4 CPU upgrades other than Newer Technologies use some sort of 'Virtual Firmware to address this issue. Newer Tech uses a patented hardware fix (programmed Xlinx chip, at least on the original G3 cards.) There is a small (4% or so) performance hit in many applications with Spec. Processing disabled. Some Photoshop 5 tests I ran in the past actually showed higher filter performance with it disabled. All 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). Performance Tips Tab: Easter Egg: Holding down the Option key when selecting the 'About' menu option (under the Apple menu) while the XLR8 control is active will show the G4 CPU revision as the last 3 digits of the '0x000..." number shown under the MACh Speed Control version number. This G4 upgrade as noted previously in the review is the latest (as of April 2000) v2.9 stepping.
Summary: Software controls were easy to install, use and worked well.
The next page describes installation of the upgrade and includes troubleshooting tips. Or you may use the links below to jump to a specific page.

Index of XLR8 MAChCarrier G4 450MHz Review Intro \| Benchmarks \| Appl. Tests \| Software Controls \| Installation \| Specs/Design \| Summary - or - Back to WWW.XLR8YOURMAC.COM
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