Very Hot CPU

[Pita]

I finally got  lm_sensors installed and now I can see why most probably my stystem freezes occationally.

In gkrellm there are 3 temp indicators. When the system freezes the temperatures read 57, 45, 75 °C respectively.

I am working in an ambient room temp of around 28°C.

There is a fan over the CPU and I have to leave one side of the housing open for lower temperature.

Is there some way to prevent the CPU from over-heating?

Since I can see the temperatures now I stop the process which is causing the heat to built up at 70°C.

Regards

[bigpaws]

Make sure the machine is clean and free of obstructions.

Bigger heat sink.

Bigpaws

[BlueMage]

Consider a water-cooling solution.

Wait, I'm assuming you haven't overclocked here.  Even running full tilt for a prolonged period that last temp seems fairly high.  Is your heatsink's fan working properly?  Are any of the extraction fans on the case malfunctioning?

[nightflier]

Also make sure the heat sink is properly attached. I remember finding one with a broken latch.

[GrannyGeek]

You also need to be sure the thermal paste is applied properly. It should be something of good quality like Arctic Silver and it should be a very thin layer, not a thick layer. Given that your CPU is overheating quite a bit, I think I'd remove the HSF, remove the CPU, clean off whatever thermal paste is there now, and put on Arctic Silver correctly.

There are links to illustrated directions for many types of processors at
http://www.arcticsilver.com/instructions.htm
--GrannyGeek

[nightflier]

Be careful with that Arctic Silver, use sparingly. Don't get it on any circuit board. Also hard to get off fingers 

[Tigerwolf]

Double check the CPU fan. 

I went through all sorts of things with a hot CPU.  The heatsink measured 120+ degrees versus about 80 normal on identical machines.   They all ran Vector Linux, even, so it wasn't related to system running load.

The heatsink and fan were clean, and the fan was spinning and looked just fine.  The very first thing I checked had been that the fan would spin freely with no power applied, so had ruled out gummy, dried out lubrication.  It  was a ball-bearing type and wasn't growling or vibrating abnormally, and since it was spinning fast, I figured the problem was elsewhere.

I changed, the CPU, measured voltages and clock waveforms, even swapped memory, all to no avail.  I'd come to the theory that the motherboard had some sick CPU interface chips that, altough working, had a failure that either was loading the CPU's output drivers, or making the CPU sink too  much current on inputs.  I'd seen this before in digital circuitry where rather than swinging from 0 to nominal operating voltage, some signals were 'stuck' at mid-voltage but could still swing enough to allow operation.

Quite by accident my finger brushed the fan while doing a measurement, and the fan stopped with virtually no resistance at all.  What I didn't realize was it was actually running slow and not moving enough air.   

Apparently the fan had a bad drive coil, or bad coil driver which made it spin slower than it should and with almost zero torque.  Replacing it solved the problem and the heatsink temp fell right in line with the rest of the boxes.

[Pita]

Thank you all!

Looked for artic silver. Seems to be unknown here. However, one technician at one shop lent me Zalman Thermal Grease. Applied it together with some cleaning and the temperature stays now steady around 30 °C. Fan speed around 3000 rpm.

BlueMage, I had a good hard laugh on your suggestion of using cooling water.

Regards

[BlueMage]

BlueMage, I had a good hard laugh on your suggestion of using cooling water.

I was being serious

(well, half-serious - I know a bloke who basically dropped his entire machine into a freezer to keep it running)

[Joe1962]

If you laughed at that, then this should get you rtofling... Get the name of one of the water cooling companies! I certainly don't want my CPU freezing, that happens quite a bit all by itself under some moderately hard windows use...

FrozenCPU has the biggest inventory of CPU water blocks, CPU water block mounting hardware, universal CPU water blocks, water blocks for Intel processors and AMD water blocks for your liquid cooled system.

Anyway, here's a review of some CPU water coolers in Tom's Hardware:
http://www.tomshardware.com/2004/09/20/7_hot_new_water_cooling_systems_tested/

[rbistolfi]

LOL, I will never buy it with that name!

On a side not, I like water cooling because they are more quite and silent. I have a beep in my ear all the time since a Metallica concert like 15 years ago, at Buenos Aires. Some problem with the equipment ends with an incredible loud sound through the 80x10³² watts amplifiers. I was right in front of them 
After that, noise is very annoying to me.

[lagagnon]

Thank you all!

Looked for artic silver. Seems to be unknown here. However, one technician at one shop lent me Zalman Thermal Grease.

You may be interested to know that a number of studies have revealed very little difference in the performance of thermal greases - one being as good as the next, despite the marketing hype and the cost differences. Glad you fixed your problem and I agree, water cooling is unnecessary in all computers except those running overclocked at full 100% CPU 24/7.

[BlueMage]

water cooling is unnecessary in all computers except those running overclocked at full 100% CPU 24/7.

Or gaming beasts.

(Not that I can talk - my beast isn't watercooled, though I am seriously considering it as a side project, if for the silence if nothing else.  The QX6xxx intel series run pretty cool considering what they're pumping out)