The supplied printed manual was a little thin, consisting of 9 pages including the warranty statement. There were no photos of typical installations, instead there were line drawings only of the the 75/7600, 86/9600 and 85/9500 motherboard/system layouts. There were installation precautions and troubleshooting sections and a good list of preferred settings however. For users that have installed other cards (PCI or CPU) in their Macs the documentation is fine, however inexperienced owners may want more details. Installing the card is simple however, and the documentation is adequate for that.

MacTell also has a installation manual available for download at their web site if you'd like to review it before buying.

Installation was of course identical to other CPU cards and only took a minute or so. As with all adjustable speed cards, most of the initial effort will be adjusting the speed of the card and finding the maximum reliable speed. If you're not the tweaker type - just set it to one of MacTell's recommended speeds (I suggest the 266 or 300 settings). If you want to get the maximum performance out of the card, then additional testing and trial and error will be required.

Although I rarely follow this advice, it's always best to back up your data before boldly going where no man had gone before.

Speed Adjustments:
The CPU speed of the card is set by two small rotary hexadecimal (0-F) switches on the back of the card, mounted at a right angle so that they are accessible when the card is installed in the system. You can leave the card set to its default CPU speed of 266 Mhz or you can try and run faster speeds by adjusting the two switches to the desired speed according to the table in the manual. Of course you adjust the switches with the power off.

Verify Reliability!
When running the card above the rated speed, always verify reliable operation at the new speed by running with CPU intensive applications for many hours. If there are any errors or failures, reduce the speed setting to a lower one as shown in the manual speed table. When errors are seen I like to reduce speeds by at least two clicks backwards to ensure I'm not running the card on the "ragged edge".

Use common sense, always start low and work up, not the other way around, which can be a disaster leading to frustration at best, and corrupted files at worst. It is foolish to have the fastest machine around if it crashes every other hour. Speed without reliability is nothing, but you don't have to sacrifice one for the other if you are careful, use quality components and spend a little time up-front in setup and testing.

To verify that 300/300 was reliable, I ran Newer's RAMometer continuously for 24 straight hours with the cover on, and saw zero errors.

The PowerTower Pro, like most PowerComputing models, does have a fan blowing on the CPU heatsink at all times. That could be a factor but considering how relatively cool the G3 CPU cards generally run I doubt it is much of a factor.

Below is a photo of a PowerForce CPU card installed in the PowerTower Pro. Although it's a close fit with the PTP CPU bracket/fan assembly, I could still adjust the switches with the card installed.

Speed Adjustment Switches (PowerTower Pro installation shown)

I've gotten feedback from a PowerCenter owner that the plastic fan/cpu bracket touches the switches on all PowerForce (PowerLogix, XLR8 and Mactell) design cards, and that some trimming may be required. I checked for this in my PowerCenter Pro, and did not have this problem, but did note that one of the speed adjustment switches could not be reached with the CPU fan/bracket installed (click here for a photo showing this). CPU speed adjustments would require removing the fan/bracket (just a few seconds) to provide access to the 2nd switch.

Installation was no more difficult than any CPU card, but if you want to explore accelerated speeds, count on spending some time up front to verify that settings you choose are really reliable. With Mactell's preferred list of settings, and the lack of a variable cache speed control you will likely spend less time than other similar cards however.

Documentation was adequate, but owners with no experience inside their Macs may wish for a few photos of the procedure. The manual did have clear explanations of the speed settings, a list of preferred settings and a troubleshooting section.

Overall I rated documentation a 7.

The next page describes the hardware features and specifications of the card. Or you may use the links below to jump to a specific page.