cooling fan not turning on while in screen saver Aspire 5100

Cooling fan does not turn on when it should while in screen save (or powersave screen off) causing an overheat and safety shutdown of laptop at 95 degrees C.

Acer Aspire 5100 laptop running 64-bit Ubuntu 8.04.3 LTS. 1 MG RAM 2 Mhz dual core AMD processor (Turion 64-bit), acpi 0.09-3ubuntu1, acpid 1.0.4-5ubuntu9.3, acpi-support 0.109-0hardy2.

This is a new issue. This machine has been running 64-bit Ubuntu 8.04 since April 2008 and this problem only recently began to occur. I would expect the fan to be turned on when necessary even when in screen saver or monitor powersave off mode to keep the cpu within acceptable operating parameters. This being a new issue is why I am not attributing this to a hardware issue and am wondering if a recent update caused a regression.

My temporary workaround is I installed a cpu temperature monitoring applet which resides on my upper panel and not only displays the current temperature but also sounds a repeating alarm whenever the cpu temp exceed 72 C.

I can reproduce this by leaving the machine alone and allowing it to go into screensaver and after some time the alarms will sound. Once I wiggle the mouse the fan will then turn on and bring the temperature back to acceptable levels.

While using the computer normally, I notice that it usually operates in the mid 50's C and the fan will turn on when it reaches 63 C and bring it back to the mid fifties.

I have not yet attempted a BIOS upgrade to see if that would help (I feel like since this is a new problem that I should not have to resort to that.)

Thanks for taking a look at this and attempting to resolve it.