G5 Quad Fans full speed after 1 min

[Francis Little]

Hi,

My G5 Quad is running current from a few days ago, but this issue has been
happening for a long time.

After about 1 min of uptime, the fans go full speed.

As soon as I query anything like CPU temp or fan rpm with sysctl, the fans
return to a normal speed.

1 min later the fans go full speed again.

I've been working round this for some time with a cron job that runs sysctl
with one of the cpu temp sensors to calm the system.

If I boot to OS X 10.5 and load the system, the fans are stable.

Does anyone else get this?

Regards