How do I debug an overheating problem on a Dell Inspiron 1564?

I have a problem with my Laptop (Dell Inspiron 1564 Core i5 4GB Ram VGA ATI Mobility Radeon HD 4300 running Ubuntu 10.10 32bit). It shuts down abruptly without even a lag in the application I am working with before shutdown. I think it's overheating problem. Actually the laptop is hot all the time when I am running Ubuntu. When I switch back to windows, even with intense load it won't shutdown or show any problem as long as I keep proper ventilation (when the air openings are blocked it does the same).

Actually on Ubuntu i don't usually do things that need much CPU power, usually surfing internet, coding web pages and sometimes playing with python and ruby. I am not enabling desktop effects so no GPU load except the normal GNOME gui.

Now as I am writing the Processor load in the panel monitor applet is 0%, Memory 11% by programs, 22% by cache. And i have CPU Frequency monitor for each of the 4 cores set to 1.20 Ghz (the lowest possible value, i am not sure if this applet does really limit CPU usage). Running sensors in terminal gave me

temp1:       +26.8°C  (crit = +100.0°C)                  
temp2:        +0.0°C  (crit = +100.0°C) 

hddtemp /dev/sda at the terminal gave me

/dev/sda: WDC WD3200BEVT-75ZCT2: 46°C

All that fine but the laptop is Really hot i can feel it in the keyboard, mouse pad is painful to touch, and the fan is always spinning. I am also placing 2 small fans running on USB under the laptop right now and the laptop is lifted over the fans so it's well ventilated.

When I am running windows it doesn't get that hot except when there is a really big load on the CPU and this is keeping me away from using Linux for everyday tasks.

Actually I don't care much for speed as I can deal with low speed it's not going to shutdown abruptly.

So please if you can help me and tell me what are the possible causes, where should I start ?

There seems to be quite a few fan/heating issues with dell laptops. My first port of call would be to upgrade the bios.

I have had systems before that over heat and the bios update usually sorts the problem. UnFortunately it depends on dells support, please check the link below.

http://support.dell.com/support/downloads/driverslist.aspx?c=us&cs=19&l=en&s=dhs&SystemID=INSPIRON1564&os=BIOSA&osl=en&servicetag=&catid=1&impid=-1&dateid=-1&typeid=-1&formatid=-1&source=-1

Hope this helps some what.

If you're comfortable with doing it, it could well be worth taking the CPU apart and blowing the dust out of the fan and heatsink area. There are likely to be loads of guides around on the web, but the overall process is documented in the Dell service manual here. You should use proper compressed air to blow out the dust, and reapply thermal paste to the heat sink.

I did this to my Inspiron 1300 that was running very hot, and it worked absolute wonders.

What kind of GPU do you have? Radeons are known to always run hot. Switching to the proprietary FLGRX driver fixes this.

There is an open bug for this on launchpad.

To lock the CPU to the lowest possible frequencies you can do this:

sudo tee /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq < /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq

Or you can choose from the list of available frequencies by doing

echo [FERQ] | sudo tee /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq

replace [FREQ] with one of the frequencies found by this command:

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies

This might help in reducing the temperature. But actually i doubt that it is the processor thats causing the problem alone, even without graphics heavy applications a GPU can get very hot if the driver is not the correct one (perfectly optimized) so you might want to try out different drivers (if available, both open and closed source and different versions). Also try measuring the temperature when the computer is using cpu vs. using gfx. Try measuring temperature while running glxgears in full screen and then when running stress -c 5 to see which one makes the highest temperature.

An other thing that is important to think of is that you properly don't really know where the temperature sensors in you computer is.

The last this that i can think of is that the fan might not work correctly (not controlled correctly by the kernel) but if thats the case i will need to research some more ;)