# Solved: CPU overheating for no apparant reason



## XJDHDR (Jun 27, 2009)

Hello everyone

A friend of mine recently gave me his old computer, which I am thinking of restoring due to the fact that it is better than what I currently have. I soon noticed that the computer kept turning itself off after a minute or so. After some testing, I worked out that it kept turning off because it was protecting the CPU from overheating. To confirm, I went into the PC's BIOS as soon after the computer started as I could. The temperature read 80*C and quickly rose to 94*C at which point the PC turned off.

By putting a piece of aluminium foil between the heatsink and CPU, I managed to make the temperature stop rising at 75*C. Another friend who was visiting at the time suggested that the high temperature was because the CPU fan was blowing air into the heatsink instead of away from it. Does this sound right to you? Could the problem even be a faulty thermometer on the motherboard, causing the motherboard to protect the CPU from a threat that doesn't exist? I would really like to get this PC in a properly running state again. Your help will be greatly appreciated.

Kind regards


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## etaf (Oct 2, 2003)

> By putting a piece of aluminium foil between the heatsink and CPU, I managed to make the temperature stop rising at 75*C.


you could make sure the heatsink is the correct way around - if the wrong way round, it does not make contactcorrectly with the CPU
also you need thermal paste between the heatsink and CPU, which would be much better than silver paper...

Does it feel very hot - BE Very CAREFUL, heat and electrical - you should be able to tell if running at 30-40c rather than 75-80c just by your hand near it.



> blowing air into the heatsink instead of away from it.


 NOT Sure, but again, you should be able to tell 
Make sure the Fan is clean of dust etc


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## win2kpro (Jul 19, 2005)

The bottom of the heatsink and the top of the processor need a good quality thermal compound between them to transfer heat, not aluminum foil. Both surfaces need to be perfectly clean before applying the thermal compound.

Blowing air into the heatsink is the preferred method of cooling. Both pushing air into the heatsink or pulling air into the heatsink will cool it, however by pushing air is a better method since it tends to push dust away from the heatsink, whereas pulling air into the heatsink tends to pull dust into the heatsink.


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## XJDHDR (Jun 27, 2009)

etaf said:


> you could make sure the heatsink is the correct way around - if the wrong way round, it does not make contactcorrectly with the CPU
> also you need thermal paste between the heatsink and CPU, which would be much better than silver paper...


How do I tell if the heatsink is the right way round? There isn't any paper in the foil I used, it is pure aluminium. I could still try thermal paste though. I just need to know where to get some (in South Africa).



etaf said:


> Does it feel very hot - BE Very CAREFUL, heat and electrical - you should be able to tell if running at 30-40c rather than 75-80c just by you hand near it.
> 
> ...Make sure the Fan is clean of dust etc


The fan and heatsink are completely clean, my brother and I made sure of that. I started the computer and let the PC stay in the BIOS for about 5 minutes with the CPU at 75*C. After this and with the PC still turned on, I could still touch the bottom of the side of the heatsink and only feel a minuscule amount of heat.

I also noticed something else. I'm not sure exactly how fast a CPU heats up but it only takes about 8 seconds for me to get into the BIOS and in that time, the CPU supposedly heats up to 60*C while the motherboard temperature still reads 25*C.

@Win2kPro
That is probably true but I needed a quick solution to my heat problems. I didn't think that a fan blowing the wrong way would cause a 60*C+ rise in temperature too.


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## win2kpro (Jul 19, 2005)

A fan pulling air through the heatsink rather than pushing air through a heatsink will not cause a 60°C rise in temperatures, however operating without thermal compound or a thermal pad will cause a rapid rise in temperatures. 

Using aluminum foil is not a thermal solution.


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## etaf (Oct 2, 2003)

{its been a couple of years now since i built PCs } but on these older machines theres a notch running along one edge of the CPU and also a matching ridge on the heatsink - so if round the wrong way (which was a problem, i have seen a few times - also on this forum) the heatsink would be slightly off the cpu at one end.
BUT as i say not sure about modern configurations. 
you can see this here




however, I would suggest paste rather than the pad shown here - dont use too much as that can cause issue to


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## BruinBeer (May 28, 2009)

Hi XJDHDR
You can try one of these online computer stores:
www.sybaritic.co.za
www.titan-ice.co.za
www.comxcomputers.co.za
_Posted via Mobile Device_


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## XJDHDR (Jun 27, 2009)

@Win2kPro
Thank you for that. Aluminium foil is better than nothing though.

@Etaf
Thanks for the video. The heatsink seems to be able to fit in all four directions. The heatsink is also very symmetrical so I don't think it matters which way round it goes.

I guess the next step is to find some thermal paste. As another test, I felt the temperature at the area of the motherboard directly behind the CPU and I was amazed at how hot it was. It was almost so hot that I couldn't keep my finger on the area in question. 

I then felt the same area of my other computer's motherboard with a similar CPU and it felt lukewarm. This seems to reinforce the theory that the problem is CPU heat not moving into the heatsink. I guess I will try find some thermal paste and tell you what happened. I do remember reading somewhere that too much thermal paste is bad. The same place also said that you should be careful when using thermal paste with silver in it.


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## avarice (Oct 19, 2009)

an aluminum foil might make it worse.
you ought have maximum contact surface between the sink and the processor. using a foil might make both the surface rugged thereby reducing the chances of heat dissipation.

your problem can be easily solved by using a better aftermarket cooler.
i'd suggest that you remove the aluminum foil and use a thermal compound instead.
It is true that too much thermal paste is bad. u have to apply only a thin layer so that it covers all the minuscule grains between the processor and the sink that hinders heat dissipation.

and all stock cpu coolers have their fans configured so that air is taken inside towards the sink. Why? because its a better option with the smaller size of the stock sink.


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## avarice (Oct 19, 2009)

have a look at the fan speed in the bios. it could be the issue as well. typical fan speeds are 1500rpm-2500rpm.
anything below 1000 can lead to rising temps.
cpu fans use a pwm signal to control the fan speeds according to the temperature of the cpu. there are possibilities that it could be messed up. set it to 100%. it might fix the issue if it was owing to a slower fan.


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## XJDHDR (Jun 27, 2009)

@BruinBeer
Thank you for the links. I have just placed an order for the thermal grease. It should be here within a week and I can then provide an update on my situation.

@Avarice
I think we have already established that I should replace the foil with thermal grease. In my first post, I noted that the PC will turn itself off due to heat without the foil whereas this doesn't happen when the foil is there. Hence, I would say that foil improved my situation.

My fan spins at 2500rpm according to the BIOS. I also figured out that the heat wasn't moving from the CPU to the heatsink. That getss rid of the faulty thermometer theory and I imagine that the CPU fan is spinning as fast as it can. I didn't see any options to control fan speed either.

I would rather try thermal grease before I try an after-market cooler. My CPU is running at stock speeds so I would imagine that the stock cooler should be able to keep up. Besides, which would I rather try buying first: a R50 thermal grease solution or a R400 after-market cooler.


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## avarice (Oct 19, 2009)

XJDHDR said:


> @Avarice
> I think we have already established that I should replace the foil with thermal grease.


din quite read the other posts.. 
good luck with your new thermal compound.


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## win2kpro (Jul 19, 2005)

If you are going to look for thermal compounds in my opinion these two are the best.

http://www.frozencpu.com/cat/l3/g8/...rials-Innovation_Cooling_Compounds-Page1.html

http://www.frozencpu.com/cat/l3/g8/..._Interface_Materials-Arctic_Silver-Page1.html

I believe that Innovation Cooling is better than Arctic Silver 5, but will only make a difference of 3-4° lower than Arctic Silver 5.

In the Innovation Cooling compounds the only difference in 24 carat and 7 carat is the amount in the dispenser.

With either of these compounds clean the bottom of the heatsink and the top of the processor with high purity 91% or better, or denatured alcohol. Make sure the contact areas are dry before applying either compound. If you use Innovation Cooling compound, since it is thicker in consistency that Arctic Silver 5 it may be necessary to warm the compound before application.

With either compound put an amount about the size of two bb's (.5g) right in the center of the processor heatsink. It is not necessary to spread either compound since the clamping action of the heatsink cooler to the processor will do all the spreading necessary.

You may be able to find the standard Intel compound TC-1996 which is a pre-loaded syringe with the proper amount of thermal compound for one application. If you happen to find the Intel pre-loaded applicator just use all the contents of the syringe in the center of the processor heatspreader and clamp down the heatsink cooler. Of course with the Intel compound the same cleaning method for the heatsink and processor applies.


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## XJDHDR (Jun 27, 2009)

@Win2k
Thank you for the links. I will bookmark those pages. However, since I haven't overclocked the CPU, I would imagine that using that thermal grease would be overkill. Also, there is the cost of getting this to me in South Africa. If I am willing to wait a month for delivery, shipping costs alone will cost $15, 3x more than some standard thermal grease which I can get from one of BruinBeer's links above. I will consider if standard grease doesn't work.


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## win2kpro (Jul 19, 2005)

With you being in South Africa I really didn't post the links expecting you to order from the site. The links, and the note about the Intel thermal compound were only posted as references to good brands of thermal compound.


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## XJDHDR (Jun 27, 2009)

I see! As I said above, if the standard thermal grease I have ordered doesn't do the job, I will consider using the grease you suggested.


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## avarice (Oct 19, 2009)

hey hold on before you order any more costly grease. 
i ran into a guy who had issues very similar to yours. he had a sink that was not properly seated on he cpu. the clips on the side of the sink that were supposed to secure the sink tightly against the cpu's face were jagged. when he removed em and sorta placed the sink witout any clips over the face of the cpu, he saw a 10-15 degree fall in his temps.
that explains why the aluminum foil could reduce the temp when u used them. the only thing it did was close the gap between the cpu's face and the sink's bottom(i ve assumed that there is some). 
i am afraid a grease wont help you solve the issue. its time you change the sink... the whole setup. 
there is an easy way how to check if the sink is faulty. 
take a thread.. a very fine one.. place it on the face of the processor and then secure the sink over it. 
after you've locked all the clips in the sink, if you are able to pull off the string(fine thread) from between the cpu and sink, your sink is faulty..
if the string offers some resistance while coming off the face of the cpu, your sink is alright...
hope this helps.


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## crjdriver (Jan 2, 2001)

Since there are different ways to install the thermal compound AND the hsf depending on what type of cpu, it would really really help if you posted what you are working on.

Just think about it for a minute or two. Do you think the procedure for installing a water pump is the same for a 1955 Chevy as it is for a 2009 Cadillac??? I do not think so. You are going to have to ge through a LOT more steps with the modern car.


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## XJDHDR (Jun 27, 2009)

@Avarice
I tried the test you suggested with a strip of Aluminium foil. I sandwiched it between the CPU and heatsink and then tired to pull it out. The foil tore itself and left a piece between the heatsink and CPU. I then tried this test again using a strip of paper instead. The paper didn't tear but there was definitely some resistance as I pulled it out.

@Crjdriver
That is correct. I can do better than explain what I have though. I have attached some pictures of what I am working on to this post. They are low resolution though since I had to take the photos with my phone's camera. In each picture, the RAM chips are there to use as a size comparison. I will also give a small explanation of each picture:
(*cpu-overheating-no-apparant-reason-*)*cpu* - It's a picture of my CPU. It's a Pentium 4 3.0GHz HT. It also uses the newer pinless design, as opposed to the older CPU which used pins.
*heatsink-underside* - The underside of my heatsink. It is perfectly symmetrical so it doesn't matter which way round you attach it to the motherboard.
*heatsink* - A top view of my heatsink. 
*motherboard* - My motherboard. Illustrates the pinless design used on the CPU.


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## avarice (Oct 19, 2009)

i know its a bit late to ask this question but still..
you sure you secured the locks after you placed the heatsink? i guess you have to press it to secure the locks and my friend says.. it will give a "click" sound when u do that.


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## XJDHDR (Jun 27, 2009)

Yes, I'm very much sure that the clips are secured. Am I correct in thinking that your suggested test would also show whether the clips are secure or not?


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## avarice (Oct 19, 2009)

hey did u say that you could remove off the paper?
i tried it with mine and i pretty much could not. the paper tore off.
i guess the sink is not pressed against the cpu tight enough. by the looks of ur cpu, it seems like an lga775 socket. its pretty common these days. why dont you try plugging in someone else's heatsink onto your motherboard? that way you can zero in on the issue.


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## avarice (Oct 19, 2009)

XJDHDR said:


> Am I correct in thinking that your suggested test would also show whether the clips are secure or not?


it is to test whether the sink is pressed against the cpu tight enough so that heat dissipation actually occurs.
sometimes, even after securing the clips, the sink might be loose on the surface of the cpu.


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## win2kpro (Jul 19, 2005)

avarice said:


> even after securing the clips, the sink might be loose on the surface of the cpu.


If that were the case, the machine would fail to boot.


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## avarice (Oct 19, 2009)

win2kpro said:


> If that were the case, the machine would fail to boot.


 not always. if the chassis intrusion was disabled, bios can load and machine would boot normally. 
heck i myself have clocked a processor to 4.8g, used a homemade tube cooler, poured liquid nitrogen into it and it worked.. did not even hook up the sink. 
chassis intrusion is not always a problem.. atleast not with modern boards.


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## crjdriver (Jan 2, 2001)

OK, you have a socket 775 type cpu. After you clean ALL parts with 99% or 91% alcohol, apply a small amount of thermal compound to the center of the cpu heat spreader. Now take the hsf and place it on the cpu however do not lock it down yet. Give it a twist or two back and forth. 

Now engage the four push pins. Do this by pushing on diagonally opposed pins until you hear them click; repeat for the other two. Now turn the mb over and make sure ALL four pins are fully engaged. Note I always recommend pulling the mb when installing a hsf on a socket 775 type.

One other item. The hsf must contact the cpu heat spreader with a min of 15lbs of clamping force. Failure to achieve this force will result in a shutdown after a few seconds.


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## avarice (Oct 19, 2009)

crjdriver said:


> One other item. The hsf must contact the cpu heat spreader with a min of *15lbs of clamping force*. Failure to achieve this force will result in a shutdown after a few seconds.


that was exactly what i was trying to bring out. the clamping force....
guess i ran out o words..


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## win2kpro (Jul 19, 2005)

avarice said:


> not always. if the chassis intrusion was disabled, bios can load and machine would boot normally.
> heck i myself have clocked a processor to 4.8g, used a homemade tube cooler, poured liquid nitrogen into it and it worked.. did not even hook up the sink.
> chassis intrusion is not always a problem.. atleast not with modern boards.


You don't understand the properties of a socket 775 LGA processor. I can guarantee you that if the cooler is not locked down where the pads make contact with the socket contacts with at least 17 (f/lb) of pressure the machine will not POST or boot.

If you check the archives here at TSG I can't tell you how many times I have had to post instructions on how to reinstall a socket 775 processor because the cooler was not installed correctly, and the machine refused to POST or boot.


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## XJDHDR (Jun 27, 2009)

@CrjDriver
Thank you for that information. My first thought would be Methalated spirits but I need to confirm it's alcohol content first. 

@Win2kPro & Avarice
That is some interesting information. I'm not sure what is meant by "chassis intrusion" though. How would the CPU/ motherboard know there is too little pressure though?

P.S. My thermal grease order still hasn't arrived. I got an email from Sybaritic (the company I ordered from) this morning saying that they have given the grease to their courier and it should be here in the next 2 - 5 days. They also gave me a tracking number. As of 10pm yesterday, it was in Johannesburg.


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## win2kpro (Jul 19, 2005)

XJDHDR said:


> How would the CPU/ motherboard know there is too little pressure though?


Your problem is not pressure related. If that were the problem, you would not be able to access BIOS. The pressure problem occurs when the pads on the processor do not contact the the contacts in the motherboard socket with a minimum of 17 (f/lb) of pressure.

When heat is not being transferred from the processor heatspreader to the cooler heatsink properly so it can be dissipated by the fan on the heatsink the temperature rises rapidly. Processors have a factor known as TDP (Thermal Design Power). This is the amount of heat that must be dissipated by the cooler for the processor to operate properly.

When the processor heat reaches a point above TDP the 1st thing that happens is the processor "throttles back" so that it is not operating at the specified specification speed. If the temperature continues to rise, it reaches a point called thermal trip which is approximately 15-20°C above TDP based on the processor being used. At that point the processor shuts down completely to protect itself from self destruction.

I would have to have the processor sSpec number to tell you exactly what the specified TDP temperature is for your particular processor. The TDP varies from processor to processor based on the core used in that particular processor and the stepping of the processor.


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## XJDHDR (Jun 27, 2009)

I see. So if there is too little pressure, the motherboard acts as if there is no CPU installed. 

I'm guessing that the TDP is about 75 - 80*C. After I placed that aluminium foil between the CPU and heatsink, my brother tested the computer's stability by playing a game using that motherboard and CPU. The game (Prototype) had a lot of stuttering while playing with the problem CPU, compared to playing the game on our other PC which uses a Pentium 4 2.8GHz HT (200MHz slower than the problem CPU) where there was very little stuttering. To make sure though, is there any way I can find out what the sSpec number is?


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## win2kpro (Jul 19, 2005)

When you get your thermal compound and get ready to apply it, clean the top of the processor so it's absolutely clean, and you should be able to see (may need a magnifying glass) a 5 digit alpha/numeric code or possibly just a 5 digit alpha code (sSpec number) etched on top of the processor, for example SL68B or SLAPP or something like the examples. 

Post the 5 digit code and I will link you to a spec sheet that will give you all the information on that particular processor.

After you get the sSpec number you can go to the motherboard manufacturers site, and make sure the processor is supported by that particular motherboard.


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## XJDHDR (Jun 27, 2009)

The thermal grease I ordered finally arrived yesterday afternoon. I applied it to the CPU following CrjDriver's instructions. The CPU's temperature now rises to a maximum temperature of about 50*C. It looks like my problem has been solved. To everyone who provided a suggestion, thank you very much.

As for the sSpec number, this is what is engraved on the CPU:
*INTEL (H)(C) '04
Pentium (R) 4
630 SL7Z9 China
3.00 GHz/ 2M/ 800/ 04A
5519A975*


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## etaf (Oct 2, 2003)

thanks for providing the update, as it always good to know the solution to the problem and will also help other people with the same problem searching
would you now mark solved
at the top of your first post is a button mark solved


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## win2kpro (Jul 19, 2005)

Here's a link to all the specs on your processor.

http://processorfinder.intel.com/Details.aspx?sSpec=sl7z9


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## crjdriver (Jan 2, 2001)

50C under load is fine. Looks like you got it fixed :up::up:


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## XJDHDR (Jun 27, 2009)

@Etaf
You're welcome. I was going to mark it solved as soon as Win2kPro provided the information on my CPU.

@Win2kPro
Thank you for all the information and help you provided.


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## win2kpro (Jul 19, 2005)

You're welcome. :up:


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## Izzeho (Aug 25, 2008)

just wanted to post and say this may fix my issue also. I never knew CPU paste could make that much of a difference, but considering how adamant so many of you are.. I'll pick some up tomorrow...

Ironically I have almost identically specced computer reaching very much similar temperatures. The computer has a completely corrupted hard drive but I'll fix that once it stays on for more than 20 seconds.


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## XJDHDR (Jun 27, 2009)

Yes, thermal grease is very important. That's why it is applied to every microprocessor that has a heatsink attached.

In my case though, I thought there was enough thermal grease applied to the CPU. Or I did at first. I was wrong though.


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