High-res PowerBook G4s (Double-Layer SuperDrive) [#6]: Fixes for sudden loss of AirPort connectivity

Today we resume coverage of an issue where Apple's new Double-Layer SuperDrive may suffer from a problem similar to one exhibited with relatively high frequency by mid-2005 iBooks -- where the kernel-task process spikes in processor usage, and AirPort connectivity is suddenly lost. Cursor tracking can also become erratic when the problem manifests.

In almost all occurrences of the issue, afflicted PowerBooks (and iBooks in the former case) have more than 1 GB of RAM installed. Memory fault by manufacturer does not appear to be a cause, as users with various brands of memory -- including Apple's own -- are suffering from the problem.

The problem is most likely to occur, it seems, under heavy network traffic conditions or under unusually high processor loads -- both of which can sometimes be generated by the use of Java-based peer-to-peer applications like LimeWire and some BitTorrent clients.

Dozens of users have now corroborated the issue.

MacFixIt reader Alex is one of the latest. He writs:

"Add me to your list of users experiencing the airport problem mentioned on your front page. I just received a PowerBook 17" with 2GB of RAM installed. I haven't been able to ascertain the cause, but the symptoms are exactly as the others have described. Cursor tracking is 'jumpy', kernel_task CPU utilization spikes, and airport drops. The symptoms can only be cleared by a reboot. Here's hoping this issue gets fixed in Mac OS X 10.4.3, because my laptop is nearly unusable as is."

Another reader, Keith Marsh, adds:

"Like many other users, I bought the new 17" Powerbook last saturday. I installed 2 gig of RAM a few days ago, shortly after doing so I get the same problem- Airport cuts out, curser sticks and flickers. I get this problem at least twice a day- Very annoying as I have to restart every time to fix."

Repeatable solution: Reducing RAM So far, the only surefire solution to this issue is to reduce the total amount of used RAM to 1 GB or less. Last week we outlined a number of potential solutions, including use of lookupd workarounds and clearing of caches -- but none seems as effective as the inconvenient RAM reduction workaround.

There are two ways to reduce the total amount of usable RAM:

Physically remove module(s) until the total amount of installed memory is 1 GB or less

Enter the following command in the Terminal (located in Applications/Utilities) followed by the return key: % sudo nvram boot-args="maxmem=1024" -- this limits the amount of memory usable by the system.

Feedback? Late-breakers@macfixit.com

• High-res PowerBook G4s (Double-Layer SuperDrive) [#5]: More on sudden loss of AirPort connectivity; Decreased video performance?
• High-res PowerBook G4s (Double-Layer SuperDrive) [#4]: Sudden loss of AirPort connectivity
• High-res PowerBook G4s (#3): Why the battery lasts longer (cont.); Some readers say new screen is worse; more
• High-res PowerBook G4s (#2): Full new feature list; Why is battery life longer?
• Apple refreshes PowerBook line: No increase in processor speed; Higher resolution, battery life

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