<b>Apple CPU upgrade cards and PowerCenter systems: a bad combo

Apple's 604e 233MHz CPU upgrade card (and other similar cards from Apple) will not work in Power Computing PowerCenter systems. The technical reason for this is detailed in the bottom of a Power Computing TechTalk web page: "The Catalyst architecture requires the DTRTY line from the CPU. As none of Apple's upgradable systems require this line, it was left unimplemented in Apple's CPU card designs. To provide support for the Catalyst design, Power has implemented the DTRTY line on unutilized and compatible pins on Apple's original CPU card design. However, because Apple's cards do not enable DTRTY, they are not compatible with Power's Catalyst machines."

This fairly noncontroversial fact led to a major dispute involving a customer wanting to return one of these cards when he found that it would not work on his PowerCenter machine. Rather than add to the heat on this issue, I will omit the details (although one participant's view can be found on the Accelerate Your Mac! site). Suffice it to say that, if you are in the market for one of these cards, and you have a PowerCenter, don't get the card.