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Review: XLR8's MACh Speed G4zTM
G4 CPU Upgrade for AIO/Beige/B&W G3s
By Mike
Published: 11/22/99
Hardware Features/Specifications/Compatibility
Intro | Benchmarks  | Appl. Tests | Software Controls  | Installation | Specs/Design | Summary
G4/400Z Technical Details


MACh Speed G4z Package Contents:

What's Included:
The following is a list of the contents of the XLR8 G4/400Z upgrade package:
  • 400MHz G4 ZIF module with 1MB of Backside Cache
  • Printed Manual (very detailed and comprehensive)
  • CD with Control Software, Utilities and Troubleshooting docs
  • Permanent Anti-Static Wrist Strap (use it)
  • Small Screwdriver (for removing heatsink clip)
  • Thermal Paste (to apply on CPU/Heatsink contact area)
  • Applicator and instruction sheet for above
  • Warranty Registration Card


The MACh Speed G4z 400MHz comes ready to install into a B&W G3 Mac (100MHz bus speed system), but the manual lists the jumper settings for 66MHz bus speed systems like the Beige and AIO G3s.

Hardware Details:

  • Motorola G4/400MHz CPU (stepping 2.6)
  • 1MB of Sync. Pipeline Burst SRAM L2 Cache
    Samsung KM736V799T-44 (4.4ns cycle time) x 2
    (225MHz rated)
    See Samsung PDF Spec Sheet for details.

Speed Settings:
Since the XLR8 G4 ZIF has jumper settings that allow different Bus/CPU ratios (which affect CPU speed directly), there is no need to change your motherboard jumper settings (which voids the warranty) as is the case with OEM or Jumperless CPU modules. Some companies like Sonnet and Newer Tech are said to be releasing ZIFs that automatically sense the bus speed of the system and select the proper Bus/CPU ratio to run at the rated speed. Although some may prefer this approach (as it's plug and play) I prefer the option of adjustable settings since it allows me to test for higher speeds (NOT Recommended that you try this however).

If you own a B&W G3, the MACh Speed G4z arrives ready to drop in. For Beige/AIO owners, you need only move the jumpers as shown in the manual before installation.

Important Note: Along with the benefits of a wide range of adjustments comes some responsibility. This card allows setting bus/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).

Overclocking is not recommended as it may void the warranty and may not be reliable. Speed is nothing without reliability and you risk your data and your hardware when overclocking any hardware. 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. For more on the risks of overclocking, see my FAQ's Overclocking Risks topic area.



System Compatibility:

The MACh Speed G4z is listed as compatible with the following Mac models:

  • Apple Blue and White (B&W) G3 (tested here)
  • Apple Beige G3
  • Apple All-in-One (AIO)

They also list the G4/400 which I suspect means the Yikes (PCI) systems which use basically the same motherboard as the B&W G3.

When used with their CarrierZIF CPU card, the G4z is compatible with the following older Macs according to their current info:

  • PowerMac 7300-9600
  • Umax J700 and S900
  • PowerTower Pro and PowerWave
  • Genesis MP 720 and Millennium

Note: XLR8's G4z PDF file for system compatibility when used with the CarrierZIF lists the PowerCenter/Pro and PowerTower which are Catalyst based Macs and not G4 compatible to my knowledge. I've notified XLR8 to verify that info. These systems are compatible with the CarrierZIF when used with a G3 CPU module however.



B&W G3 Firmware Notes:

As most readers know, the Firmware update 1.02/1.1 prevents a G4 CPU from working in a B&W G3 (proven here back in August, 1999). XLR8 supplies a Firmware Updater that removes the G4 CPU block. See the Illustrated Installation Guide for a walk-through of the software and hardware installation of this upgrade in a B&W& G3.

Test System Hardware Summary

  • Apple B&W G3
  • 256MB SDRAM
  • Stock 6GB IDE hard drive
  • 32X CDrom drive
  • ATI Rage128 Orion PCI Video card (in 66MHz PCI Slot)
  • OS 9.0, VM off, QT 4.03 Pro, QD3D 1.6.,OpenGL 1.1.2, [No Libmoto]


Summary: The hardware design has proven reliable in use, and the firmware patcher worked flawlessly. OS 9 was installed after the firmware update.


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

Index of XLR8 MACh Speed G4 400MHz Review

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

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