iMac G5 - Loud Fans After Single-User Mode

[Andy C]

Hi Guys,

I have one of the iMac G5 1.8 (Rev A) machines and it's always been fine, right until installing update 10.4.6.

Since that update, whenever I enter single-user mode (Apple-S at startup) the fan spins right up as it normally would, but when I reboot the fans stay at full belt. Before 10.4.6 they used to spin down again as the machine rebooted. Properly shutting down and disconnecting the power has no effect, the fans are still full steam ahead the second I power up.

Currently the only way I can fix it is to take the rear panel off and hit the SMU reset button. Things are then fine until I go back to single-user mode. Admittedly it's not that often, but it's still an annoyance that shouldn't be happening.

I was hoping 10.4.7 may have fixed something, but alas no.

Anyway, does anyone know why this happens, and why it's a recent development since 10.4.6? I always thought the SMU was controlled by the firmware, and not the OS. If it is controlled by the OS, have Apple changed anything?

I'm just looking for ideas.

Regards,

Andy.

 

[jonah22]

With my G5, the fan would spin to full speed every now and then after I enter single-user mode. The solution for me is to shut down *and* unplug it for a few minutes. Try it, it's easier than re-installing the system!

-Jonah