G5 firmware 5.1.8f7 (#2): Fan, sleep issues

We previously problems with strange activity during system sleep or system wake after installing the the Power Mac G5 firmware update 5.1.8f7, which only applies to G5 models released in mid-2004.

More readers have now confirmed the issue, with some interesting observations.

Brian Leslie writes "After installing the 5.1.8f7 firmware update last week (with no problems) I have had 4 encounters of the monitor not waking from sleep after prolonged non-use of about 8-10 hours and the fans on my Dual 2.5 going full blast. The only thing I could do was power down with the switch on the front. Upon restart everything works fine with no indication of a crash or kernel panic. I tried an Archive and Install back to 10.3.4 and then an update to 10.3.6 with the combo updater with no change."

"Then last night I set my monitor to not sleep with just the screensaver coming on. Everything was fine this morning after about 7 hours. Then when I came home tonight the computer was off. This was about 10 hours later. I don't know how long the computer had been running during the day but when I booted up the computer everything appeared fine with no indication of a crash or kernel panic.

"I called Apple this morning and they said there's no way it's the firmware update (which I find hard to believe) and that I should disconnect all my external USB and FireWire devices and that's sure to fix it. Besides that I was told to reset the PRAM, the PMU, delete a PowerManagemant.plist file and run the Hardware Test CD. Not sure if any of these things will fix this problem."

Jeffrey Osterman writes "Add me to the list of people experiencing strange problems after updating to 10.3.6 and firmware 5.1.8f7 on my dual 2.0 G5. Every couple of days (since the update) the computer crashes hard (usually while I'm not in the room) and I come back to find it with the screen off and the fans running full bore."

It should be noted that excessive fan activity will not result in damage to your G5. The increased activity is a protection measure implemented in the G5 architecture that turns the fans on at a higher speed if a signal is not received from Mac OS X indicating the proper speed. This causes the fans to perform at their highest cooling capacity.

Feedback? Late-breakers@macfixit.com.

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