Apple has released a new version of the Power Mac G5 Uniprocessor update (5.1.5f2) which presumably resolves a host of problems reported here on MacFixIt (see previous coverage), specifically an issue where some units more picky about RAM -- i.e. modules that previously functioned properly now cause operational problems including system freezes. The problems were more prevalent on Power Mac G5 1.6 GHz models.
Apple's instructions for the new update state "Remove any third part RAM before installing this Firmware Update. After the Firmware Updater has verified that it has been completed correctly, you can re-install your third party RAM.
After downloading the update, you will have to run it from its installed location at Applications/Utilities.
Full instructions are as follows:
1. Download Power Mac G5 Uniprocessor Firmware 5.1.5f2 update
2. Save changes to open files and then quit all other open applications, if necessary.
3. Open the firmware updater (in Applications/Utilities)
4. Click Shut Down in the Firmware Update window to start the update. Wait for your computer to shut down, quit any applications and save changes if necessary.
5. Press and hold in the Power button on the Power Mac G5 until you hear a long tone or see the Power button light flashing.
6. The firmware updater starts automatically. A status bar shows the progress of the update. You may see more than one status bar.
7. After the update is complete, your system restarts automatically. When a message says your computer's firmware has been successfully updated to version 5.1.5f2, the update process is finished.
The original Power Mac G5 Firmware Update (5.1.5f1) was released to fix a previously reported issue where single-processor G5s -- generally 1.8 GHz models -- refused to sleep.
The 1.7 MB Power Mac G5 Firmware Update 5.1.5f2 is available via a
download link on Apple's Web site, or through Software Update.