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Vortex375

Member

Registered: 2009-02-24

Posts: 61

Notebook overheats (only when running Linux ?)

Hi everyone,

since a few weeks my notebook computer has repeatedly shut down due to overheating. The symptoms are:
First, the system becomes very slow. Eventually the screen will go blank (the system does not shut down, though). If you touch the keyboard (on the top side of the machine) it feels HOT. And a rather bad smell of hot plastic and electronics emits from the ventilation opening,

Of course, I shut the machine down as soon as I notice one of the symptoms above.

This has started to happen about a month ago. At first I thought it was a one-time thing, but then it began to happen more and more frequently.

I thought this was clearly a hardware fault, but then a friend pointed out that the overheating always happens when the machine is running Linux and has never happened under Windows.

Which is true: I have a dual-boot environment as I use Microsoft Windows for gaming. Games usually put the machine under very high load, but I never had issues with overheating. I once went to a LAN party and the machine ran for 3 days straight, under heavy load and in a very hot room without any problems.

The overheating typically happens when the machine is not under heavy load - like when I'm browsing the web with firefox.

There also is something interesting I noticed:

When the overheating starts, the temperature monitor on my desktop suddenly shows 0°C and the fan keeps running at lowest speed (which is probably the cause for overheating).

Is it possible that the Linux kernel is controlling the fan speed based on the values it gets from the heat sensor and somehow it messes up big time?

Is it possible to prevent the Linux kernel from controlling the system fan?

TL;DR:
Machine overheats. I suspect it is because the Linux kernel throttles the system fan. Is it possible to prevent it from doing that?

Last edited by Vortex375 (2010-09-12 11:18:46)

karol

Archivist

Registered: 2009-05-06

Posts: 25,440

Re: Notebook overheats (only when running Linux ?)

I don't think the kernel controls the fan, some other app does. What hardware do you use? What do you use for checking the temperature etc.?

kagerato

Member

Registered: 2007-09-10

Posts: 45

Website

Re: Notebook overheats (only when running Linux ?)

The kernel does control the basic CPU power management policy.  In particular, there's the config section on "CPU Frequency Scaling".  If you set the default policy as "performance" and disable all others, I believe that will effectively lock the CPU (and all cores) at maximum clock frequency and thus maximum power use.  However, the OP makes it sound as though the fans are disabled sometimes...

Concerning fan control, are the fans running correctly in Linux (some) of the time?  Are they always working right in Windows?  Usually you can hear roughly how active they are even in quiet systems if you put your ear up to the vents/panels even if you can't get a direct RPM read out.  Also, what fan control options are set in the system BIOS?

There are relevant ACPI kernel options for the fan and processor thermal zone in addition to the CPU frequency ones.  They're under the ACPI section, naturally.  Normally these are built as modules in most stock kernels.  (I usually build them right into the kernel, as I see no reason to ever disable or unload them.)

As for userspace utilities, there are packages related to this.  Check out acpid, cpufrequtils, powernowd, and pm-utils.  This page on the Arch Wiki may help.

You should be able to read the current processor power state out of /proc.  Try "cat /proc/acpi/processor/CPUx/power" where x is the core number.  Mine shows, for example, an active state C0 with a max cstate of C8.

Since you mentioned gaming, is there a discrete (separate) GPU installed in this notebook?  By that, I mean a full-board graphics chip connected over an AGP or PCI-E slot, not a built-in or on-board graphics processor.  Those separate GPUs in notebooks often cause heating problems, since they're both power-hungry and contained in a very tight space.  Power management (fan options) for the GPU have traditionally been handled in user space.  Look into what graphics driver you're using in X and then check the relevant man page for any options on frequency or fan controls.

As always, examine "dmesg" and your log files in /var/log for anything interesting.  Good luck.