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Accelerate Your Mac! - the source for performance news and reviews
The Source for Mac Performance News and Reviews
Review: MAChCarrierTM G3/500 CPU Card
10X G3 CPU Upgrade for PCI Macs
Published: 11/02/99
Documentation/Installation
Intro | Benchmarks | Appl. Tests | Software Controls | Docs/Installation | Specs/Design | Summary
MAChCarrier Manual and Installation Information
The MAChCarrier comes with an 88 page (+ a fold-out speed settings chart) well illustrated manual. The manual has been revised recently and now includes more information, a revised troubleshooting section, and a revised speed chart with bus speed settings up to 66MHz. It currently is the most detailed manual I've seen with any upgrade. I did spot a few minor typos but if you've seen the documentation included with other upgrades, you'll be pleasantly surprised at this one.

The new manual contains illustrated guides to installing the hardware and software. Configuration information as well as troubleshooting and advanced tuning sections are also included. For those not familiar with CPU upgrades, there are explanations of the basics and interaction of Bus, CPU and cache speeds to help clarify their relationship to each other. XLR8's toll-free tech support number is also listed in case you have questions or need assistance.

XLR8 supplies a permanent (vs. the disposable one time use versions) adjustable anti-static wrist strap which I recommend you use. Often you may not destroy an electronic component from static discharge, but you shorten its life which can lead to sudden failures down the road.

If you're considering a CarrierZIF bare card and a non-XLR8 ZIF module, I suggest you read my Setup Guide to the CarrierZIF first. MAChCarrier cards come with a ZIF CPU module already installed and ready to use so I won't repeat that guide here.

If you have a non-Apple Mac model in most cases you will want to remove the black support bracket. This will allow the card to be used in low profile systems like the PowerComputing and other clone machines (the bracket is left on for support in most Apple brand Macs).

The following is a summary of the CPU card installation routine:

  1. Install the XLR8 Software (do this first, especially if you own an Adaptec wide SCSI PCI Card as noted in the XLR8 2940UW Tech Note) .
  2. Shut Down the Mac (disconnect the AC power cord to prevent accidental powerups should you inadvertently press the keyboard power-on key, etc.)
  3. Attach the wrist strap and connect it to the monitor out jack on the back of the Macintosh.
  4. Remove the case cover
  5. Remove the existing CPU card from its slot
  6. If possible - remove the L2 cache dimm. Most G3 upgrade problems are due to too slow an L2 cache. with the G3 card's fast backside cache you don't need it and especially with Apple's stock cache dimms - most will be a source of problems. (In 1997 I wrote an article on 8500 cache upgrades that has the steps involved in those systems, but read the precautions first. 7x00 Macs and most clones have far easier access to the Cache dimm - check your system manual for info. 95/9500 macs don't have removable cache and neither do most Genesis systems or Umax J700/S900 models.)
  7. Double check that the CarrierZIF speed settings are correct (manual has table of settings). I strongly recommend you leave the card set to the factory settings for at least several days before you think of changing speeds.
  8. Insert the CarrierZIF card (making sure it's fully seated)
  9. Press the CUDA (CPU reset) button on the motherboard (hold for 30 seconds)
    (Note: Zapping the PRAM or resetting the CUDA switch in systems with a Thunder3D or IXMicro IX3D card can result in no video at boot. If this happens, remove the video card, power up the mac, shut down and then reinstall the video card.)
  10. Replace the Case Cover
  11. Power up the Mac.

Total installation time was under 5 minutes, but if you want to experiment with other than the default speed you will need to adjust settings and then verify that the new speeds are reliable (I'd suggest at least 12 hours of heavy apps use to verify reliability along with an overnight RAM test or Game continuos demo). Should your system not boot follow the steps in the troubleshooting section of the manual and the tips noted below.


PowerComputing Install Notes: Take care when installing any PowerComputing fan bracket as it can contact the CarrierZIF switch levers and change the settings of the switch.

For PowerComputing PowerCenter/Pro owners with the plastic CPU Fan bracket, I suggest you trim the two topside protruding tips of the plastic bracket back about 1/8" with a pair of scissors so the bracket slides back in place easily. This does not affect support as the bracket U channel that holds the card edge remains intact. Take a look at this modified bracket photo. It took 10 seconds to trim the tips back. My PowerTower Pro 180 has a metal bracket and did not need trimming.


Below is a picture of the card installed in my Genesis (9500 motherboard based system):

CarrierZIF in Genesis

Speed Settings:

As mentioned earlier, the CarrierZIF card has adjustments for 40 to 60MHz Bus speeds (as well as some undocumented 60+MHz bus speeds) and up to 10X Bus to CPU ratios (10X ratio requires a 10X G3 CPU of course). See my Setup Guide to the CarrierZIF for more details on switch settings.

Troubleshooting: Along with the benefits of a wide range of adjustments comes some responsibility. This card allows setting bus and CPU speeds to rates beyond the rating of the CPU and possibly your system's capability. You need to consider the installed ZIF module's rating and the limits of your particular Mac (don't start out with high settings that have not been proven reliable in your system/CPU module combination). Although the XLR8 manual covers troubleshooting problems, here is a basic guide I follow when experimenting with speed settings in my Macs:

  1. Before any major upgrade, especially when experimenting, back up your data just in case.
  2. As a starting point, I set the card to a low bus speed (45MHz or less if I don't know the machine history). If it has a 400MHz ZIF module I set the bus speed to 50MHz and ratio to 8 since that is a must to run 400MHz [50 x 8 = 400])
  3. I double check that the ratio setting is correct (set to so that bus speed times ratio does not exceed the CPU speed). Don't rush, take the time to verify that the settings are correct per the manual. It is important to not overclock the CPU or cache during the process of finding a reliable bus speed - you want to isolate one factor for reliability, not confuse the issue by running the CPU or cache beyond its rated speed.
  4. If the system does not boot at the current bus speed setting and I've made sure the card is fully seated and I've removed the L2 Cache dimm (if possible - some systems have soldered-in cache, so deinterleaving RAM or lowering the bus speed are other options) then lowering bus speed may be the only option (after verifying your CPU/Bus ratio setting is within CPU's rated speed limits).
  5. Once the system boots, I verify reliability by running applications that stress the CPU for hours to make sure the card is reliable. Simply booting and running MacBench is not proof. If you own Unreal or Quake, letting the auto-play demos run for hours is a great way to test for problems.
  6. As a test for hard drive data errors - try mounting an Apple .SMI file image which will do a checksum test. (Apple often supplies software updates in this format.)

Warning/Disclaimer: Overclocking may void the warranty and may not be reliable at all speeds. I do not recommend overclocking to others and you assume all risk from doing so. Although owners reports in my 2200+ entry Rate Your G3 Upgrade database indicates overclocking is very common, often the reported speeds may not prove reliable after extended use. Check with XLR8 on their current warranty policy if you plan on overclocking the card and are worried about warranty support. No company can guarantee overclocked speeds or what bus speed will be possible in your system. Buy a CPU upgrade by its rated speed, not an assumption that you can overclock it reliably or will be able to repeat other owner's speeds.

Bus Speeds: The CarrierZIF design in my experience has allowed the fastest bus speeds across more Mac models than any G3 card I've tested to date (and I've tested most every brand of Mac CPU upgrade since 1997).

This list below is only for reference, based on my experience - not a guarantee you can repeat these results as each Card/System combo is somewhat unique (CPU lot/batch, motherboard revision, installed RAM quality, cache, software and addon components all can affected speeds and reliability).

Based on tests of two different revision CarrierZIF cards with XLR8 CPU modules installed, I have found the following bus speeds reliable on my Macs which contain good quality RAM in matched pairs and are free from any other existing hardware or software problems.

  1. Genesis: (9500 motherboard): up to 55Mhz bus speeds with interleaved RAM.
  2. 9600/350: Up to 55 MHz bus speed with interleaved RAM, 60MHz bus speed with RAM deinterleaved.
  3. PowerCenter Pro: Up to 60MHz bus speed with no L2 cache dimm installed.
  4. PowerTower Pro: 50MHz bus speed (L2 cache dimm had to be removed). There have been past reports that some PowerTower Pro 250 (and 225) systems that may have problems with the CarrierZIF but XLR8 has revised the design to improve this. Although the problem may be resolved in the current CarrierZIF design, I still recommend PTP owners contact XLR8 or their dealer to ensure their models are 100% compatible. My system is a PTP180 with rev 4 (5000-0121-04) motherboard. Most PTP250s have a rev 5.


Summary: The MAChCarrier/CarrierZIF printed manual was without a doubt the best I've seen with any CPU card to date.

Installation went smoothly and the card plugged and played first boot when left at the factory set bus and CPU speed. As with any adjustable CPU card - things can be complicated if you want to experiment, as only trial and error can determine what advanced settings are reliable in any particular Mac. My CarrierZIF Setup Guide lists the rules I follow when searching for maximum reliable speeds.


The next page describes the hardware features and specifications of 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

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