400MHz G3 Upgrade Cards

When we last evaluated G3 upgrade cards (see "Born-Again Macs," February 1999), 400MHz G3 accelerators for pre-G3 Power Macs were just coming to market and were so prohibitively expensive that we could not recommend one. Prices have since come down, and with a couple of new manufacturers joining such familiar faces as Newer Technology and Sonnet Technologies, time was ripe for a second look.

We tested seven 400MHz G3 accelerators that plug into the processor slot of the Power Mac 7500, 9500, and 9600: Mactell's PowerJolt 400/200, met@box's JoeCard 400/200, Newer Technology's Maxpowr G3 400/200, Phase 5's Maccelerate 750, PowerLogix's PowerForce G3 400/200, Sonnet Technologies' Crescendo G3 400/200, and the XLR8 Mach G3 400/200. Most of the cards also work with some Macintosh clones from Power Computing and Umax Technologies.

All of the cards boosted the performance of our test platform, a Power Mac 9500, approaching the speed of our 400MHz reference system. However, although prices have fallen dramatically, these cards still aren't inexpensive, and you may find that it's best to save your money for a true G3 Power Mac.

Most of the cards installed easily, although you may have trouble if you want to accelerate a Mac clone housed in a low-profile box. The Newer Technology and XLR8 cards have removable brackets so they can fit in the smaller enclosures, but the other cards are too large. Mactell's PowerJolt was a tight fit in our test system, and it requires a separate power connector for a cooling fan that's mounted to its heat sink.

Most of the cards feature switches to change the CPU speed or other settings. The PowerForce G3, PowerJolt, Maccelerate 750, and JoeCard all feature rotary switches, but in the latter two, the controls are inaccessible when the cards are installed. The Mach G3 has 12 DIP switches that you can set from the top. The Maxpowr G3 has four DIP switches to set which Mac model you're using. The Crescendo G3 was the only card that dispenses with switches altogether, largely because it doesn't let you change CPU or cache settings.


To gauge performance, we ran CPU benchmark tests using the MacBench 5.0 Processor test (see "Speed, but at a Price") and also timed typical operations in Adobe Photoshop 5.02. There was some discrepancy between the two sets of tests. MacBench showed a small but noticeable gap in CPU scores between the slowest and fastest cards, and a couple of cards nearly matched our reference system, a 400MHz Power Mac G3. The Photoshop tests (not shown) yielded a narrower speed difference among the cards, but here the blue Power Mac clearly outpaced all of the cards.

Why the difference? The system bus in the blue Power Mac G3 is much faster than those in older Power Macs, so the new G3 systems should be faster than older Macs equipped with G3 upgrades. The MacBench Processor score emphasizes CPU and cache-bus speed over system-bus speed, while Photoshop relies more on overall performance.

Nevertheless, both sets of tests showed relatively little difference between the fastest and slowest cards. The top performer was the Maxpowr G3, followed by the JoeCard. The slowest card was the Mach 3, which nevertheless boosted our Power Mac 9500's performance well past that of a 300MHz Power Mac G3. Newer Technology introduced the Maxpowr at $1,599, making it prohibitively expensive, but after two rounds of price cuts, you can now purchase the card for a much more reasonable $749.

Most of the cards let you boost performance even further by stepping up the CPU speed (a process called overclocking) or increasing the speed of the cache bus. For example, when we boosted the Maccelerate 750 to 440MHz, the card outpaced our reference system in the MacBench CPU test. But again, the reference system was faster in our Photoshop tests.

Although you can get a performance boost from overclocking, we don't recommend it because it can lead to frequent system crashes. You can test your system's ability to handle the higher speeds by running Apple's Graphing Calculator–or any other appropriate software–in demo mode overnight. If your system is still running in the morning, it's likely that you can get away with overclocking.

Aside from the Sonnet and Newer Technology cards, all of the accelerators give you the option of stepping up the CPU speed by setting DIP or rotary switches. However, to access overclock frequencies on the Maccelerate 750, you have to cut a trace on the circuit board, which voids the warranty.

By default, all of these cards run the cache bus at half the CPU speed, hence the "400/200" in most of the model names. However, some cards include software that lets you experiment with faster cache-bus speeds. You can get a slight performance increase, but again at the potential cost of frequent system crashes. The Newer Technology and XLR8 cards have automatic sensing features that prevent you from using cache speed settings that won't work.

Different Power Macintosh families have different system-bus speeds, and we found that some cards handle the variations better than others. The Maccelerate 750 operated reliably at a bus speed of 53.7MHz, but the XLR8 card, at its default bus setting of 50MHz, could not boot in a Power Macintosh 9500, which uses a 50MHz system bus. We had to reduce the card's bus setting to 49.1MHz to run our tests.


Compatibility has improved tremendously since Macworld last tested G3 upgrade cards. Previously, we found that some cards had trouble booting from disk arrays or running Retrospect backups due to architectural differences between Power Mac G3s and older Power Mac systems. Since then, most of the vendors have released software that fixes the problem. In this round of testing, all of the cards successfully booted from a disk array connected to an Adaptec 2940UW Ultra Wide SCSI board. We also ran a series of Retrospect backups to a SCSI DAT drive without any errors.

However, some compatibility issues remain. With any G3 upgrade, you may notice display artifacts due to conflicts with the Power Mac's built-in video. The only remedy is to install a PCI graphics card. In addition, Apple will not guarantee that Mac OS X and its successors will run on older Power Macs with or without G3 upgrades.

All of the cards ship with control panels and/or system extensions needed to enable the acceleration. You can use the control panels to set cache speed and other options. Mactell's control software features a cluttered interface that resembles a race car's dashboard but does display the current CPU and cache speeds so you can tell if the card is working.


Prices for 400MHz G3 upgrades have fallen dramatically, but they're still on the high side, ranging from $699 to $959. Because the performance differences are minimal, price and ease of use should be the key buying factors. Fortunately, the top performer in our tests, Newer Technology's Maxpowr G3, is heavily discounted from its original $1,599 price tag. We also liked Sonnet Technologies' Crescendo G3, which features a three-year warranty.

The lower prices make these cards worth a close look, and it's likely that prices will fall even further. You still may be better off saving your money for a Power Mac G3, but if you have a heavy investment in your existing hardware or you don't want to give up a six-slot machine, then consider one of these accelerators.

Speedy G3 Upgrades
Company Product Mouse Rating List Price Contact Pros Cons
Mactell PowerJolt 400/200 3.0 mice $699 888/622-8355 Is inexpensive; decent performance. Poor documentation; installation requires separate power connector.
met&#64b;x JoeCard 400/200 3.0 mice $945 949/862-1180 Has good performance; three-year warranty. Is a little expensive.
Newer Technology Maxpowr G3 400/200 4.0 mice $749 316/943-0222 Is fastest performer; good software. Has no overclocking option.
Phase 5 Maccelerate 750 3.0 mice $849 610/586-5703 Works at faster bus speeds; decent price. Overclocking voids warranty.
PowerLogix PowerForce G3 400/200 3.5 mice $959 888/769-9020 Has flexible speed settings; decent performance; three-year warranty. Is a little expensive.
Sonnet Technologies Crescendo G3 400/200 3.5 mice $699 800/786-6260 Is easy to install; three-year warranty. Has no overclocking option.
XLR8 by Interex Mach G3 400/200 3.5 mice $879 888/957-8867 Good software and manual; fits in low-profile clones; high-quality wrist strap. Didn't work at default system-bus speed.

July 1999 page: 36

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