Replace CPUs to speed Macs

Upgrade: Keep your computer and its devices, improve performance -- and save money.

May 24, 1999|By Dave Zeiler | Dave Zeiler,Sun Staff

High-tech veterans often lament the reality that even top-of-the-line computers are outclassed by better and cheaper models six months later.

The average user begins to feel the twitch to upgrade when new software, particularly games, won't run on his model. And each month it gets worse.

Until recently, Mac users had two expensive choices: Spend $1,000 or more to upgrade the machine with a new CPU (the chip that serves as the computer's "brain" and the component primarily responsible for speed) or buy a new Mac for $2,000 or more.

However, the cost of both options has dropped dramatically in the past year. You can buy a new iMac with a speedy 333 MHz G3 CPU in your favorite color for $1,200. The original bondi blue 233MHz iMacs are available for $900 or less.

If you're still using a pre-Power Mac and you're itching to make the leap to the PowerPC chip, you're better off going this route. No upgrade for a "68K Mac" will deliver anywhere close to the performance of the cheapest iMac.

But Power Mac owners, particularly those with heavy investments in memory upgrades or serial and SCSI devices -- which can't connect to new G3 Macs without adapters -- may want to hang on to their old machines for a few more years.

Luckily, the cost of upgrading the CPU has dropped even more dramatically than the price of a new Mac. More than half a dozen companies offer CPU upgrade cards for almost every Power Mac-- including many PowerBook laptops -- for as little as $299.

While upgrades exist for even last year's Macs, older computers based on the PowerPC 601 chip will benefit most -- as much as a 1,000 percent speed boost, depending on how much you spend.

Before buying a CPU upgrade card, shop around. Make your first stop a Web site called Accelerate Your Mac (, which has exhaustive documentation as well as reviews of many upgrade cards.

You'll find vendors aplenty, including Newer Technology, Sonnet, Vimage, XLR8, MacTell and PowerLogix. Almost every week, one or the other cuts its prices.

To install the upgrade yourself, you should know your way around your Mac's innards. While most vendors ship decent instructions, there's no substitute for inside-the-box experience with such tasks as adding memory to your Mac.

I recently bought a CPU upgrade for my home system, a Power Computing PowerTower Pro 180 (from the fleeting days of Mac clones). As a veteran Mac-do-it-yourselfer, I was undaunted by the task of yanking the original CPU "daughtercard" from the motherboard to replace it with the new one -- a 275 MHz G3 Railgun card bought from an online Mac vendor, Bottomline Distribution, for $359.

I followed my computer's original documentation for opening the box and the Railgun's documentation for installing the card. It's vital that you read all the instruction before starting.

G3 cards require software (usually a system extension and a control panel) to operate to their full potential, so you should install these before you perform surgery on the Mac.

Proceed with caution. Static electricity discharged from your hands can turn high-tech hardware into useless junk in an instant. When the computer's cover is off, be sure to wear an anti-static wrist strap or frequently touch the machine's power supply.

I had no problems inserting the G3 card into the daughtercard slot. As a precaution, I also removed the existing Level 2 cache memory module, which improves CPU speed. All G3 upgrade cards come with this cache memory on board, but you may find that you have to leave your old cache memory in your computer or the Mac won't start up. The upgrade card vendors advise trying it both ways.

With the hardware in place, I booted my PowerTower and discovered that the software provided with the Railgun card would not load -- disabling my cache memory altogether and slowing the computer.

After many attempts and much hair-pulling, I decided to try other vendors' software, which was available on the Web. To my relief, several programs worked. I settled on Sonnet's extension for its Crescendo cards; it seemed to be the most compatible.

Many people would (and should) stop here, but I'm a speed freak. I took advantage of two dials on the Railgun card that allowed me to "overclock" it -- that is, run it at higher speeds than advertised.

Nearly every G3 upgrade vendor includes such dials (only Newer Technology shuns them), but none encourages the practice and several warn overclocking voids your warranty. I overclocked the Railgun to 325 MHz before the system became unstable. I backed it down to 318 MHz.

I'm pleased with my G3 upgrade. MacBench tests show I've more than doubled my speed, giving performance equal to a new, 300 MHz G3 Power Mac.

While upgrading your Mac to G3 speed is a lot more complicated than, say, plugging in a Zip drive, the benefit is worth the effort.

Now, if you'll excuse me, I have to get back to that Tomb Raider demo.

Send e-mail to david.zeiler@

Baltimore Sun Articles
Please note the green-lined linked article text has been applied commercially without any involvement from our newsroom editors, reporters or any other editorial staff.