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G4 Processor Upgrades

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At a Glance
  • Giga Designs G-celerator GC5B-1400-D2/A 1.4GHz

  • Other World Computing Mercury Extreme G4/1.4-1.467GHz

  • PowerLogix PowerForce G4 Series 100 1.4GHz

  • Sonnet Encore/ST G4/1.4GHz

Your old Mac is sitting there getting older and, if your mind isn’t deceiving you, slower. Apple’s Power Mac G5 has arrived on the scene, but that doesn’t mean you can’t get more life out of your G4. If you have a Power Mac G4 (AGP graphics and later models), you can upgrade to a 1.4GHz G4 processor. We tested Giga Designs’ G-celerator GC5B-1400-D2/A, Other World Computing’s Mercury Extreme G4, PowerLogix’s PowerForce G4 Series 100, and Sonnet’s Encore/ST G4. A $600 investment will give you a Mac almost as fast as Apple’s other G4 systems, and it could keep you satisfied for another six months to a year.


Installing an upgrade card is pretty easy, as long as you read the instructions and move carefully. Giga Designs’ documentation is nicely illustrated and easy to follow, as is OWC’s. PowerLogix’s one page is brief, but it covers the basics. Sonnet’s manual is the most thorough, with installation illustrations of all compatible systems; however, it doesn’t mention that the Apple System Profiler won’t report the correct upgrade speed unless you install Sonnet’s free Sonnet X Tune-Up software (available on the company’s Web site).

To set the speed of the OWC and Giga Designs cards, you must configure jumpers, which can be tricky. If you set them incorrectly, your upgrade will either run slower than it should or become unstable. Be sure to check the processor speed with the Apple System Profiler as soon as you install the upgrade so you can shut down the computer and reset the jumpers if necessary. If you use your computer at too high a speed, the processor can overheat and damage the upgrade or motherboard.

Having control of the processor gives you the option of setting the jumpers for overclocking. All these upgrade cards use Motorola 1.4GHz G4 chips, but OWC sets its card slightly faster, at 1.467GHz. Giga Designs tests its card at 1.5GHz, and it even tells you how to set the jumpers if you want to overclock.

Slightly goosing the speed of the chip probably won’t cause damage, but we don’t recommend it. Overclocking causes the chip to run hotter; over time, the heat may damage your processor, hard drive, or subsystems. And you aren’t likely to notice an improvement after going from 1.4GHz to 1.5GHz.

Sonnet sets bus speed for you—so you don’t have to configure any annoying jumpers. But it doesn’t come with a heat sink or fan. You have to remove the heat sink that was attached to your original processor and attach it to the Encore card. While reinstalling the old heat sink isn’t difficult, you may have problems down the road.

The Sonnet upgrade card comes with a thin layer of a creamy heat-conducting substance. Once the upgrade is installed and running, the pad adheres to the heat sink, efficiently pulling heat off the processor and dissipating it. But if you need to reinstall the original processor or decide to move the upgrade to another computer, the thermal paste pulls apart like peanut butter between two slices of bread. The documentation doesn't mention this, but you should go out and buy a tube of thermal paste if you plan on moving the processor to another system.

The PowerLogix card comes with its own heat sink and fan, and it doesn't require that you set jumpers. But you do have to take the fan off to install the card, and getting the screws in through the tall heat sink is a challenge. To provide the additional power the large fan needs, you have to plug the fan into a drive power connector.

How Fast Is Fast?

The four cards were nearly identical to each other in terms of speed, and they all dramatically improved the overall speed of our 500MHz Power Mac G4. The upgraded system was twice as fast as the original computer on processor-intensive tasks, such as rendering video in Apple's iMovie 2.1.2. In fact, the G4 with any of the four upgrade cards was just barely slower than a 1GHz Quicksilver Power Mac. Our original G4 still had a slower graphics card, which made Quake painfully slow. It also had a slower hard drive. (But combined with a more powerful video card, such as ATI's $150 Radeon, it should provide better results.) The upgraded test system was a better overall performer than the current (1GHz) eMac. And unless you're a hard-core gamer, these upgrades are comparable to Apple's current systems, and at around $600, they're also $200 cheaper than Apple's least expensive offering, the 1GHz eMac.

The Sonnet and OWC cards work in a wider variety of systems than the PowerLogix and Giga Designs cards; the latter two cards are only for 100MHz-bus systems. For the same price, PowerLogix sells a PowerForce G4 Series 133 1.4GHz card for Digital Audio and Quicksilver models. Giga Designs also has a $589 card for 133MHz systems.

With the $60 Sonnet Cube Dealer Installation Kit, Sonnet's card will also work in a G4 Cube. Another option for Cube owners is PowerLogix's $599 PowerForce G4 Series 100 for the Cube.

Macworld's Buying Advice

Now is a great time to consider an upgrade card if you desperately need a new system but aren't ready to place an order for a Power Mac G5. Any of these four cards will rejuvenate your older computer, but the Sonnet card is a good choice only if you're sure you won't move it after installation. On the other hand, the OWC card works in the widest variety of systems and is relatively easy to move between systems. It's the best choice for an office with a variety of computers.

All cards are compatible with Mac OS 9 and Mac OS X.

At a Glance
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