Mac OS X 10.4.8 Special Report: Increased fan activity

Some users have reported dramatically increased fan activity and noise after updating to Mac OS X 10.4.8 -- particularly with G5-based systems. This is an issue that has appeared with other incremental Mac OS X updates, and there a few effective fixes:

Reset 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.

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 Douglas Vaught writes:

"Since updating an iMac G5 at home and at work to Mac OS X 10.4.8 the once super-quiet computers now run their fans almost continuously. I have tried various CPU settings to no avail."

Index:

• Release Notes: Delta vs. Combo; Enhancements in this release, more
• Update procedure recommendation: How to apply Mac OS X 10.4.8
• Common workarounds: Resolving typical incremental update issues

• Adobe Illustrator: Problems with pathfinder function, other issues
• Audio issues
• Black border around cursor 
• Burning media issues
• Classic: Problems starting up; launching apps
• Closed-lid portable functions broken
• Display coloring issues: Blue tinting and more
• External devices (USB/FireWire): Not recognized; can cause issues after system updates
• Finder Crashes, other issues
• Flash: Slowness caused by new version
• Incomplete update: Installing Mac OS X 10.4.8 stalls or otherwise fails
• Increased fan activity
• iSight difficulties: "In use," won't turn on, more
• Math problems in Rosetta applications
• Menu items: Disappearance, other issues
• Mighty Mouse problems: Scrolling, more
• Non-launching applications (including Rosetta apps): Fixes
• Printing issues -- fixes
• Safari Issues: Bad plug-ins, caches, more
• Spotlight issues
• Startup problems: Stalls, extremely slow booting, more
• Universal Access: New features, processor usage questions
• Wireless connectivity (AirPort, etc.) issues and fixes

Resources