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My computer turns itself off unexpectedly after some time of use. It appears that this might be temperature related, but not for sure. I installed 2 tools that monitor temperature: SpeedFan and CPU Thermometer. The only definite finding is that there is a sensor (labelled temp1 in SpeedFan and CPU in CPU thermometer), which shows a temperature of 108C a second before the computer powers down. Until that moment, this sensor shows a constant temperature of 40C.

I can usually reproduce the shutdown by viewing a few movies together, which cause another sensor (labelled CPU in SpeedFan) to go up to 60sC, but I do experience the problem even at times when this sensor remains low and cool. It does seem that the problem is more frequent if the computer is turned back on immediately after shutdown, but not always.

I have had other hardware problems recently, which might be related:

  1. My hard disk heated up. I installed a fan on it, which worked to reduce the heat. The hard disk sensor shows around 40C.
  2. I had occasional blue screens and hard disk failures. Replacing the power supply seems to solve both these issues, but then this powerdown problem began appearing.

I would appreciate any suggestions as to how to determine where the fault is, or what needs to be replaced.

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4 Answers 4

This sounds a little bit like your motherboard is dying, at least in my ears. A faulty sensor can trigger such behavior, but do also check if all the fans/heatsinks are probably seated.

You also may wanna consider that it is a problem with the new power supply. Did the problems directly start after swapping it?

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This is almost certainly a heat issue. If you are spiking to 108c, your computer is almost definitely shutting itself down. It is either shutting down because of intense heat, or the motherboard is set to do an emergency shut down at a certain temperature.

Even being in the 60s is considered somewhat high. Should still be stable, but at that point you need to be concerned.

Check your CPU fan. Is it working? If so, are your other fans in your case working? Good rule of thumb is to intake air towards the bottom of the case and exhaust at the top (heat rises). Make sure none of your exhausts are clogged with dust or anything.

If you can confirm this is a temperature issue, you may need to reseat your CPU with some fresh thermal compound.

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I think he confirmed already the temperature issue. The main problem is that the sensor is obviously updating only on the last moment, before the safety cut. –  Gnoupi Apr 19 '10 at 14:56

+1 for defective sensor, motherboard or power supply. Also it is not uncommon for a faulty PSU (you have already replaced one) to fry some of the connected components.

You can also check your motherboard capacitors to see if some of them are swollen or leaked.

You can also try to find the same motherboard from some shop and see if your PC works with replacing that.

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up vote 0 down vote accepted

It appears as though a faulty sensor is the problem. I changed 2 settings in the BIOS - one to enable the fan to adjust its speed to the temperature, and the other to disable shutting down when the computer heats up. Not the ideal solution, I know, but the computer no longer powers down, and all sensors report normal temperatures.

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