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April 13th, 1999

PowerJOLT 400 MHz Upgrade Card Makes Your Mac Go Zoom

PowerJOLT 400 MHz
Upgrade Card
Contact and Other Information
MacTell - US$999

Outpost - US$899

Manufacturer: MacTell
Web Site
Description: G3 Upgrade Card
Address: Mactell Corporation
7000 Cameron Road
Austin, Texas 78752

Price: US$999
Telephone: 888.622.8355
Fax: 512.323.6394
System Requirements
Power Macintosh 7300, 7500, 7600, 8500, 8600, 9500, 9600. Power Computing PowerWave, PowerCurve, PowerCenter, PowerCenter Pro, PowerTower, PowerTower Pro. UMAX/SuperMac S900, J700.

The Macs We Used
Power Computing PowerCenter Pro 240

128 MB RAM
UWSCSI Hard Drives
Dual Monitors IMS Twin Turbo 8MB Video Card On Board Rage II 4 MB

PowerComputing PowerCenter 150

128 MB
Ultra-SCSI Hard Drives

PowerJOLT 400

The PowerJOLT 400 is a 400 MHz G3 upgrade card for PCI PowerMacs and compatibles. It comes with a 1 MB Backside Cache at a 2:1 ratio and retails for US$999 directly from MacTell or US$899 at online retailer Other online retailers are priced around US$899 range as well.

The package comes with documentation, an installer disk with all needed drivers, and the PowerJolt itself.

We tested this card on a PowerCenter Pro 240 (referred to as the 240 in this review) and a PowerCenter 150 (referred to as the 150 in this review). Our Final Score and MacBench 5.0 results are at the bottom of the review. The card is 100% compatible with the computers listed in the gray panel to the right.


The PowerJOLT 400 was a snap to install, literally. We installed the PowerJOLT INIT and Control Panel from the floppy included with the card. We then pulled out the original daughtercard and snapped in the PowerJOLT into the PDS (Processor Direct Slot) slot of the 240. Even if you have never opened your computer before, you should find this an easy job.

We did encounter some difficulties installing the unit in the 150. The card did not exactly fit the slot. MacTell's tech support helped us with this. After their instructions we filed down an indentation to make it fit which worked fine. Most users should not have to undergo this type of surgery. Having only one PowerCenter 150 to test this on, we are not sure if this is a problem with the computer or the upgrade card.

The PowerJOLT series include two dials that control clock speed. The dials are located on the back side of the card. They are easy to use, but in most machines they are not accessible once the card is installed. One dial controls the bus speed and the other controls the clock multiplier. This is similar to what PC users do with jumper settings when they clock up their machines. The dials are decidedly easier to use than messing with jumpers. The two in combination let you decide how fast to set your card. Included in the package is a spreadsheet on all your possible combinations and the card comes preset with the proper settings. The PowerJOLT 400 MHz card has a maximum setting of 424 MHz. Our 240 comes with a processor fan, but Mac owners without fans needn't worry. The PowerJOLT 400 comes with a heat sink fan right on board the card that keeps the processor extremely cool (66 degrees Fahrenheit on our 240).

Startups Breeze By

Once the card was installed, we turned on the machine and watched the extensions and control panels zoom across the screen. The startup times on both machines ended being a little over twice as fast as it was before.

Apps too, were much faster.

The Mac Observer is an enormous web site, with more than two thousand items. Managing the site is made possible by Adobe GoLive, but the size of the site was wearing down the PowerCenter Pro 240 before the upgrade. With the PowerJOLT installed, we were able to shorten the time it takes to manage the site by about 15%. That is a stunning figure when you consider that the majority of site management has nothing to do with CPU speed. In general, CPU intensive activities were about 250-300% faster from with GoLive, a percentage we found to be consistent in other apps like Photoshop 5.0, Pagemaker 6.0, Flash 3, and FileMaker Pro 4.0.

Non-processor intensive apps did not see any kind of noticeable real-world speed increases as they already ran very fast before we installed PowerJOLT 400. App launch speed increases alone may be enough for many users to purchase this card.

Games rocked.

The 240 was no slouch in its day. It was one of the fastest desktop computers on the planet and was the first Mac to offer a 60 MHz bus speed (a bus that is not utilized by the card which maxes the bus speed out at 53 MHz). None the less, games like Unreal, Myth, Myth II, and Quake were worlds better. Frame rates were faster and games were very smooth. Myth II frame rates are as high as 30 fps at 640 x 480 in full software rendering mode (no 3D accelerator) with a consistent 20 fps during battles. At 800 x 600 in software rendering mode, we got as high as 18 fps and a consistent 12-14 fps during battles. Performance with Power3D card from Techworks looked just as good as it did before the G3, but game play was smoother. Myth II is a particularly 3D intensive game and the frame rates we achieved in software rendering mode made the game extremely playable.


We of course did what many of you would do. We ran the card as fast as we could to see how well it worked. On the 240, we were able to run the card at 424 MHz with the Backside Cache set at a 2:1 ratio (the ratio the card is rated at) consistently. This is the highest possible clock speed the card allows and the only glitch we encountered at this speed was having difficulty starting the system up when it was cold. Restarts were flawless, but starting up in the morning was sometimes difficult. Dropping the card back down to 416 solved this problem.

On the PowerCenter, we found that the card was very stable at 404 MHz. Interestingly, we were able to run the cache at a 1.5:1 ratio, though after a couple of weeks we dropped it back to a 2:1 ratio when we encountered some stability issues. Setting it at the rated 2:1 ratio cleared up the problems.


The documentation is the one area that MacTell needs to improve on. For instance we found the instructions to install the PowerJOLT control panel and INIT 7 paragraphs into the documentation. Reality says that is about 5 or 6 paragraphs before most users stop reading and start installing. Also, there were not enough directions for installing the card into the many machines it is designed to fit. It was MacTell tech support that told us that we should break off the portion of the card designed to make it fit in models like ours. Lastly we felt that the directions for setting the clock speed of the board were not as thorough as they should be.

To their great credit, tech support was equipped to handle all these issues. In addition, MacTell is working on new documentation that should be coming out in the near future.

MacBench 5.0 Results

MacBench Scores for the PowerCenter Pro 240 running at 400, 420, and 424 MHz


MacBench Scores for the PowerCenter 150 running at 400, 420, and 424 MHz

Note: The PowerJOLT 400 results on the PowerCenter Pro 240 run slightly faster than the PowerCenter 150. This is to be expected as the PowerCenter Pro had essentially the same motherboard (based on the Apple PowerMac 7200 motherboard), but one that had been tweaked to get slightly higher performance. 

Final Score (Maximum score is 5 Gadgies)

4 1/2

The card performed fantastically, but we had to dock a little for the poor documentation. We confidently recommend this card for anyone looking to turn their Mac into a speed demon.

Purchasing Links

MacTell - US$999

Outpost - US$899

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