Mixed in with the flurry of issues surrounding Apple's new PCI Power Macs - including difficulties with Open Transport and numerous printing problems - there have been reports of slow Ethernet performance and outright crashes on the Power Mac 7200/90. Apple last week confirmed the problem exists and announced plans to fix the problem. Only the Power Macintosh 7200/90 model is affected by this problem; neither the 7200/75 nor any other Macintosh model are impacted.
What's the Problem? The built-in Ethernet on the Power Macintosh 7200/90 may fail to correctly send large packets over an Ethernet network regardless of the network protocol being used. This can cause connections to time out, give poor performance, or in some cases lock up the machine.
The trouble stems from the design of the built-in Ethernet on the 7200/90, which is timed from a clock generator ASIC; other Macintosh systems clock built-in Ethernet off a dedicated clock chip. Apple has reworked the logic board of the 7200/90 to include a dedicated clock chip, and all units currently in manufacturing incorporate this change. This problem does not impact the 7200/90's printer or modem ports, and (obviously) does not cause trouble if the built-in Ethernet on the machine isn't in use.
Apple has posted detailed information about the problem on commercial online services and in its Tech Info Library. I had trouble locating the article in the Tech Info Library, but Ric Ford has made the text of Apple's release available on his MacInTouch Web site.
Which 7200/90s are Affected? Power Macintosh 7200/90s with serial numbers before xx543xxxxxxx may exhibit the problem. Serial numbers greater than xx544xxxxxxx incorporate the reworked logic board and don't have the problem.
However, just having a 7200/90 with a serial number in the right range doesn't mean every network trouble is attributable to this timing problem - plenty of other things can cause slow network transfers and (yes) crashes. If you're having trouble, Apple recommends troubleshooting your Ethernet connection to see if the problem might be network-related. It's also probably a good idea to install the latest version of Open Transport (currently 1.0.8) and the 7.5.2 Printing Fix 1.1 (if you print) to see if those help your performance. (See the previous article about the 7.5.2 Printing Fix for more information.)
If You're Affected... Apple has announced it will replace motherboards on 7200/90 systems at no cost so long as the unit's serial number is in the specified range; contact your Apple dealer or call Apple at 800/SOS-APPL. Apple claims customer complaints on this issue have been limited to a few calls from large corporations. Though reports on online services and Usenet have been more extensive, it's difficult to tell whether some of the problems reported are due to this hardware issue or unrelated network problems. The bottom line seems to be that if you own a 7200/90 in the serial number range and rely on its built-in Ethernet, it's probably worth investigating Apple's logic board replacement.