Fan speed

[Kojot89]

I have a problem with laptop fan, which is verry annoying in silent room. On Ubuntu 9.04 amd64 first the fan starts quiet, but after a few minutes it gets higher speed and keeps that speed, even if the computer doesn't need it.
On Windows XP OS the fan sometimes start's going faster, but then it slow down again, on Ubuntu - never.
I've tried using toshset -fan and speed changes, but I can't reach the lowest option.

[Rubberman]

I think the fan speed is determined by how hot the motherboard is getting. You can reduce the amount of heat produced by making sure that you have enabled ACPI in the bios (and boot), then you should be able to tell Ubuntu to throttle the CPU speed (reducing heat generation) while running. Note that the more CPU your software needs, the faster (up to max MHz the CPU supports) the CPU will be run unless you specifically throttle it down (slowing down the system). In any case, DO NOT try to slow down the fan yourself, or you are likely to end up with a toaster and not a computer...

[Kojot89]

My ACPI is enabled and I've turned on CPU option - "On demand", which means, that CPU's are in 100% of frequency only if it is needed. Otherwise they are in 50% of their frequency.
What else can I do to reduce heat emission?

[Rubberman]

It could be that the ACPI isn't properly detecting the actual temperature of the system. This could be due to a faulty bios or other issues. At this point I have made all the suggestions I can think of except for possibly updating the BIOS in your system. You can go to the manufacturer's web site and see if there is one available.

[Kojot89]

I've updated BIOS recently. But thanks for suggestions.

[D-cat]

Laptops notoriously report the wrong temp to the OS. Windows drivers know this and ajdust the speed appropriately for the known offsets. Linux couldn't do this very easily just for the large variety of laptops out there.

You're actually lucky. Most problems I see with the fan speed are of the oposite direction, the fan doesn't ramp up soon enough and the processor overheats. You can try booting with acpi=off noapic , which will (or should) leave all the power control features in the hands of the BIOS including the fan. This will have other less desireable effects as well though, such as hitting your battery life and simply powering off (soft) may cease to function.

As annoying as it may be right now, my advice is to let sleeping dogs lay.

[Rubberman]

Laptops notoriously report the wrong temp to the OS. Windows drivers know this and ajdust the speed appropriately for the known offsets. Linux couldn't do this very easily just for the large variety of laptops out there.

Spot on! In fact, each computer manufacturer (not just laptops) that support Windows tweaks the HAL (Hardware Abstraction Layer) interface to the system for just that sort of reason. IE, every OEM distribution of Windows is tailored for their hardware. It's kind of hard for Linux to do that, though some system vendors that have supported Linux versions, such as Dell, do just that for their supported Linux distributions. That usually means they are somewhat behind the curve for current software. For example, Dell supports Ubuntu 8.10 on its laptops, not 9.04 or 9.10 as yet. However, if you get a Dell with Ubuntu, you are pretty sure that this sort of stuff will work out-of-the-box.

[Kojot89]

I've cleaned the cooling system once again and now the fan is working silencer. It doesn't slow down, but it's not as annoying as it was before.
Thanks for answer. Maybe it is luck, that system take care about computer temperature so early.