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Review: OWC's Mercury G4/500, G4/400 & G3/500
ZIF CPU Upgrades

How they compare in a Blue & White G3/350 System
By Mike
Published: 10/19/2001
(revised 10/26/2001 for G4/400 results)
Installation Notes and Tips
Intro | Benchmarks  | Apps/Game Tests | Installation | Specs/Design

Rather than repeat the photos, etc. that OWC has on their web site installation pages (see links below), I'll note some important pre-installation tips and things to check before you install the upgrade. Note I did not use any thermal paste, etc. when testing these - only the stock B&W G3 heastink. (Since there is no thermal paste shipped with the upgrades I tested as most end users will - with the stock heatsink, no fan on it and using the stock thermal gasket still on the heatsink as it ships from Apple.)

IMPORTANT NOTE for Beige G3 and All-in-One G3 Owners: Although not a problem with G3 CPU Upgrades, if you're installing a G4 CPU Upgrade in a Beige G3 (1998 series) - check the Voltage Regulator Module in your system first . Newer Tech was the first company to note that "Royal" Brand modules in some Beige G3s can damage G4 CPU upgrades. Powerlogix notes it also can damage the motherboard. The Apple G3 section of the FAQ here has a question titled "How can I identify which type of VRM I have in my Beige G3?" with details, or just read this scan of the Newer Tech warning brochure.
If you don't know where the VRM is located, see this photo from my 1998 G3-ZONE troubleshooting page. The "Royal" VRMs are rare apparently, but check this before installing a G4 CPU in your Beige G3.

Blue & White G3 Firmware Patch for G4 CPUs: As noted here in past reviews of G4 ZIF upgrades in my B&W G3, the 1.1 firmware of that model cannot use a G4 CPU upgrade without a firmware patch. The patcher should not be run from OS X or classic mode (boot to OS 9). You have to run the patcher before installing the G4 CPU upgrade in the B&W G3. If you're installing a G3 you can ignore this. My B&W G3 was patched back in November 1999 during the XLR8 G4/400 ZIF review (shown in the install page of that review). OWC has a copy of the Newer Tech patcher (called "B&W G4 Enabler") available at their software/tech page.

Check the CPU Module Pins: Before installing any ZIF module, check the underside of the ZIF for any bent pins and residue from the anti-static foam (not seen on these ZIFs which were packed with a different anti-static pad, but several readers noted they'd had problems with some Sonnet ZIFs which must use a different antistatic foam material.) If you notice the CPU module has any bent pins, carefully straighten them in both axes with a small flat blade screwdriver as shown in the photo below:

straighten bent pins

Heatsink Clip Orientation: As noted in the FAQ here and past reviews - for proper cooling take note of the orientation of the heatsink retaining clip when you remove it. The clip has two slots in one end - make sure the two-slotted end of the clip is oriented the same way when you put the clip back on (after installing the new ZIF CPU module). The clip has an off-center "Bend" (pressure point) that must be over the CPU side of the ZIF for proper cooling. On the B&W G3, the two-slotted end of the clip faces the Dimms slots; on the Beige G3 the two-slotted end of the clip faces the closest edge of the motherboard.

As I noted earlier, in my Blue and White G3, I needed no addon software to enable the cache - however in a Beige G3 or older mac (via CarrierZIF card, etc.) - you will need software to enable the backside cache of all G4 CPU upgrades I've seen. (Although many G3 CPU upgrades may have the cache enabled without requiring software addons for Beige G3 and later Mac models. Pre-G3 Macs will need enablers regardless of G3 or G4 CPU upgrade type.) OWC's tech center has links to Newer tech's cache enabler software, has a free cache profiler for this purpose and XLR8's software costs about $15 for non-XLR8 card owners. If you have to run cache enabler software, make sure you check whatever software you use for OS version compatibility. (The database of CPU upgrade owner reports is also a good place to check for Beige G3, etc. owner reports on G4 upgrade reports from users of various software cache enablers.)

The OWC Mercury ZIFs are OEM (original equipment manufacturer) models and therefore have no documentation from the ZIF manufacturer. However OWC has illustrated web page guides to installation in Beige G3 and B&W G3 Macs. (The G4/PCI "Yikes" is the same motherboard as the B&W G3, except you don't need to patch the firmware.) I've also included a link to my CarrierZIF setup guide for older Macs owners that want to use these ZIFs wtih that base card:

Illustrated Install Guides: For jumper settings and installation information see the following articles:

If problems arise, check OWC's Troubleshooting page. My FAQ also has a Troubleshooting G3 Upgrades topic area.

System Compatibility:

The OWC Mercury ZIFs are compatible with the following Mac models:

  • Apple Beige G3 and All-in-One G3
  • Apple Blue and White G3
  • Apple G4/PCI ("Yikes")

Using a ZIF socketed card (XLR8 CarrierZIF, CarrierZIF MPe, PowerLogix Zforce) as a base card, you can use the Mercury ZIFs with the following Mac models. (The list below is based on previous info I have, check with the vendor of your carrier card to verify system compatibility.)

  • Apple: 7300, 7500, 7600, 8500, 8600, 9500, 9600
  • DayStar Genesis MP720 or later, Millennium
  • UMAX S900 & J700.
  • Power Computing PowerWave, PowerTower Pro, PowerCenter*, PowerCenter Pro*, PowerTower*
  • Power Computing PowerBase (for CarrierZIF MPe and ZForce cards only - original CarrierZIF model not PowerBase compatible.)

* Catalyst based motherboard Macs cannot use G4 CPUs due to a motherboard hardware issue. You can use G3 upgrades in these models however.

Carrier CPU Card Usage Notes: If used in a Carrier card for older Macs, remember the G4/7400 CPU has a 9x max bus/cpu ratio - so you'd have to run higher than 50Mhz bus speeds (55.55MHz) to run the G4/500 CPU at its rated speed . The G3/500 has a 10x max ratio and would run at 500Mhz with the card's bus speed set to 50Mhz and the ratio set to 10x on the Carrier card. (Manyof my older Macs have run 55Mhz bus speeds fine, but the L2 cache and RAM installed can affect maximum reliable bus speeds. (For Macs with L2 cache on a dimm, it's best to remove it from the motherboard with most G3/G4 cpu upgrades.) Some Catalyst motherboard based Macs (i.e. PowerCenter Pro models and PowerTowers [not PowerTower Pros]) shipped with 604 CPU cards running a 60Mhz bus speed but Catalyst motherboards cannot use G4 CPUs due to a hardware issue. (Missing a signal that is required for the G4 CPU I'm told.)

About L2 Cache in Older Macs: As a general rule, if possible remove any L2 cache dimm from your Mac before installing a G3 card which has a much faster backside L2 cache on the upgrade. In some Macs like the 9500, 9600 (up to 9600/233) and Umax S900/J700, the cache is soldered to the motherboard and cannot be removed. This cache is usually not a problem with CPU upgrades however and can be disable via software with XLR8, Newer Tech and Powerlogix's software. Of course the Apple G3 and later systems do not have motherboard cache so those owners can ignore these notes.

Overclocking may void the warranty and may not be reliable. Check with OWC on their current warranty policy if you plan on overclocking the CPU and are worried about warranty support. No company normally guarantees specific overclocked speeds.

Troubleshooting: Along with the benefits of a wide range of adjustments comes some responsibility. The CarrierZIF card (and Apple motherboard jumpers) allow setting bus and/or 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. OWC has a Troubleshooting page that may be of help should you problems.

The next page has photos of the G4/500 and G3/500 OWC ZIFs as well as their CPU revisions and part numbers. Or you may use the links below to jump to a specific page.

Index of OWC Mercury ZIF Review Pages

Intro | Benchmarks  | Apps/Game Tests | Installation | Specs/Design

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