Laptop overheating within 15 minutes

[Larnu]

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Hi,

We have recently started using Live knoppix at university. We use a wide range of OS's, including Windows, Mac OS X, serveral Linux distro's including SuSe and knoppix, and Unix. However my laptop is having a disagreement, or rather the CPU, with the Live version of Knoppix. After taking logged readings from my laptop the temperature rises at first at an incredible rate and continues to until it reaches about 90 degrees, were quite simple, Knoppix suddenly realises what's happening and shut's down. the problem is that i therefore can only do 30 minutes work on the OS, before i have to cool my laptop down... I discovered that if i get a fan and blow it at the CPU it doesn't die, but that's impracticle. Therefore i need a way to lower the clock speed of my CPU, so that it doesn't heat up so much, and hopefully won't over heat at all.

my CPU is a AMD 64Bit Althon 3000+. I also have 512Mb of Ram as well as a GeForce 5700FX GFX card, so i know those all meet requirements. I can ru n Suse fine on my laptop (infact i get much more out of the battery than I do Windows, and it doesn't get hot at all), so i must assume that either there is some sort of capatibilty problem in Knoppix, or quite simply, the fact that it runs Live, means that my laptop, quite simply, gives up the game with the constant CD access.

I would appreciate any help on this topic, however please note that my online time is limited and Linux doesn't my modem (well not Knoppix anyway), so I will most likely reply to say i have recieved your feedback and then later that day, or the next day, i will make a response on my progress with it. This is jsut because I will be on Windows the whole time I am online, and therefore can't load knoppix to test something out, and then switch back, as my time left, would be small.

Thank-you for taking your time to read this, and thank-you in advance for any help you can offer.

[unclebubbles]

If youre talking about 90c , thats dangerously hot even for an AMD cpu. Live distros are pretty hard on a cd/dvd drive, and things are pretty cramped in a laptop. The cd drive may be getting hot and the heat transferring to the cpu. But i wouldnt think it would get any hotter than it would watching a movie. Does it work ok with movies? Underclocking the cpu may help a little, but personally, i wouldnt do it just so i could run knoppix. But if you want to try it, you may be able to change it some from the bios, depending on which mb/bios you have. I can go as much as 27%, but yours will probably be different. You might try "Puppy Linux", instead of knoppix. Its a neat little distro that loads into and runs from ram, so it frees up your cd/dvd drive. It doesnt have as much in it as knoppix, but they pack alot of stuff in a small package. I think its around70mb uncompressed. It may do what you want.

[rcgreen]

To be suitable for a laptop, an OS should be able to manage
cpu speed, cooling fan etc. Maybe the knoppix live cd is not
a good choice for this type of use.

[Zelmo]

To be suitable for a laptop, an OS should be able to manage
cpu speed, cooling fan etc. Maybe the knoppix live cd is not
a good choice for this type of use.

To expand on that, there is software that can control the CPU's frequency so that it doesn't go full-bore all the time and overheat. But on many distros, that software isn't included in the default installation. If you were running a distro from the hard drive, you could install that software yourself to overcome the overheating problem. But a live CD may not let you do that.

[Larnu]

Firstly, about using a different Distro, that isn't exactly an option. All my coursework for Linux is designed specifically for Knoppix. The good thing however is that i do have a FAT32 Hard Drive as well as a FAT32 SD Card in my PC, now if i can run a program to control the CPU off that, then I might be more successful.

[antidrugue]

Therefore i need a way to lower the clock speed of my CPU, so that it doesn't heat up so much, and hopefully won't over heat at all.

I assume here you are using Knoppix 5.0 (why not use the latest version?).

Managing CPU frequency can by done directly within the kernel, no need to use a software that will do it in userspace.

First, load the module that will control your CPU clocking, for your AMD 64 cpu :

modprobe powernow_k8

Then you need to load the module that will take care of how the CPU speed is managed (cpu frequency policy). I suggest you use "ondemand" (adjust depending of the work load) here, or even "powersave" (always lowest frequency) :

modprobe cpufreq_ondemand

Then, make sure you set the default policy right :

echo -n "ondemand" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

There are many other things you can do with your CPU and its frequencies. I suggest you investigate the directory /sys/devices/system/cpu/cpu0/cpufreq/ to learn more.