Mac OS X 10.4.7 Special Report: Increased fan activity -- fixes

CNET staff

Sept. 2, 2009 7:29 a.m. PT

3 min read

Some users are reporting dramatically increased fan activity and noise after updating to Mac OS X 10.4.7.

MacFixIt reader Geoff Powell writes:

"Since updating to 10.4.7 on my Dual G5 I've had increased fan activity. Even opening Safari and accessing a site gets the fans racing away."

Fixes

Resetting the SMU In some cases, resetting your Mac's SMU -- system management unit (per Knowledge Base article #301733 for the iMac G5 or Knowledge Base article #300341 for the Power Mac G5) -- can return fans to normal operation.

MacFixIt reader Ian Williams writes:

"I have just applied the 10.4.3 combo update on my iMac G5. Repaired permissions before and after. The iMac is now starting normally but the fans are spinning very noisily and won't settle down. [...] Follow-up on my last report of fan noise and keychain problems after updating to 10.4.3. Resetting the SMU appears to have resolved both problems."

Failing an SMU reset, try starting up in Open Firmware mode (by restarting your Mac then immediately holding down the Command, Option, O and F keys simultaneously) then entering the following commands, pressing return after each:

reset-nvram

set-defaults

reset-all

Change Processor performance settings In some cases, a workaround that has been successful in previous instances of this problem has also been effective: Using the Energy Saver pane in System Preferences to change processor performance settings. Some users experience decreased fan activity when setting the processor performance at "Maximum" or "Highest" while others find decreased activity with the "Minimum" or "Reduced" settings.

MacFixIt reader Ulf writes:

"On my Dual G5 with 2.5 GHz the fan activity also increased dramatically. Unfortunately none of your suggestions helped to solve the problem: neither resetting the SMU nor resetting the NVRAM. The only thing that helped was to set the CPU usage to 'minimal' (you also can use 'maximum') in the energy saver settings. But that's not a good solution for this problem... I'm really disappointed about Apple because this is the same problem we got almost a year ago with Mac OS X 10.3.8."