High cpu temperatures after replacing the motherboard
 

Hi people,

I'm using a PC (desktop) and I replaced the motherboard two days ago; (I had an intel and replaced it with an asrock G31M-S). All other components (processor, case, video card, memory modules and wireless card) are all the same I used before. Now, the problem is I'm having high temperatures; if I go to the BIOS, it shows about 43ºC - 47ºC (about 103 ºF), and 32ºC for the motherboard (91 ºF). On windows I use a program which came with the motherboard, named OCtuner, and it shows pretty much the same temps, and sometimes hit 50 ºC, just by browsing the net (although this program is used to overclock, I'm not overclocking yet). On linux I use lm-sensors and the computertemp gnome applet; both show 58 ºC - 61 ºC just by browsing the net and listening music (?!); it has reached 70 ºC even!. Also, on windows I've had a couple of sudden reboots when browsing the net, but I'm not sure if it's the motherboard who's reboting the system to avoid overheating, or if it's windows (or the OCtuner app).

Now I have some questions: 1) is it possible that debian shows more than 10 ºC in comparison to the BIOS and windows, or is it just that debian (or linux in general) causes the cpu to heat more? 2) in case the cpu is actually overheating (as it seems to be), how could I solve this? Should I reinstall the cpu (taking it out, cleaning, reapplying thermal paste and installing it again, etc)?

I'm not a hardware expert; in fact this is the first time I do such a thing like replacing the whole mobo, which basically means reassembling the entire system (actually, I'm surprised the computer booted perfect from the first time after replacing the mobo :D).

P.S.: The reason why I changed the motherboard is because I'm planning to overclock the system in the future (if possible), but the intel one doesn't have the option to overclock. The motherboard is an asrock G31M-S as I said before, and the cpu is a 2 ghz core 2 duo (model E4400). When reinstalling it, I applied a thin layer of thermal paste to both, the cpu and the heatsink, but maybe in my noobishness I applied a bit more than what it's needed? Also, the cpu cooler is the sotck one and the brand of thermal paste I used is "thermaltake".

(Sorry for the long thread, I jus wanted to explain the problem the best I could).

Greetings, and thanks in advance.

The easiest...

What does google say about expected normal temperature and what temperature did you have with your old motherboard? Have you tried to measure the CPU temperature after you have run a CPU stress program? I would tend to trust the BIOS reading more than a temperature reading program.

Have you looked at the air flow paths to the CPU cooler, insuring that there is a ready flow from the outside to the cooler and back out? What happens when you take the the cover off your cabinet?

The easiest thing to do is to reinstall the CPU to see if that makes a difference. You can also check to see that your installation technique is good enough, if there is too much or too little paste, if you aren't applying even pressure or not enough, etc.

Were it I, I would take the motherboard out and look at the CPU mounting from both sides of the board before taking it out, using a flashlight and a small mirror to peer under the heatsink from the side to see if everything seems seems to be seated, look at the all the mounting points to see if they balance the load, or if one side of the heatsink is higher.

You can always buy a heftier CPU cooler, and you will probably need one if you are going to OC, but it would be good to know if you have a heat problem and to do something about it beforehand.

Disassembly and assembly is work, but, like mounting a CPU, is also experience and the acquisition of a skill. Also,remember that any small mis-assembly or poor contact may mean that your system will not POST, and is not yet the right reason to panic.

The length of your post helps it to fulfill the minimum prerequisites for this.

http://www.linuxquestions.org/linux/...Ask_a_Question

If the bios is not showing a temp problem then it is a virtually certainty that it is a problem with the program(OS independent).

Lm_sensors is notorious for being off (in the absolute sense). You can go through and "dial in" the lm_sensors conf file(specific to each motherboard) to get it to match (within a degree) of what your bios says. Same goes for voltage readings. Personally I no longer bother with dialing it in. Instead I just watch for a change in what is being reported.

You probably applied too much paste, and did you clean off the old paste ? Look, just clean it all off (with something like 99% isopropanol) and apply just a small drop of paste to ONLY the heat sink then clamp it down onto the board and lock it.

See here:
http://benchmarkreviews.com/index.ph...1&limitstart=4

TexMex brings up a good point. What exactly did you do for thermal transfer? Did you pull the tape off of the thermal pad on the heat sink? Did your heat sink come without a thermal pad and you didn't add any compound? Did you add thermal compound on top of the thermal pad on your heat sink? Sorry, but since I don't know you, these questions have to be asked.

My preference is to scrape off the junk that comes on these coolers and use a thin layer of Arctic Silver (or equivalent). It has generally superior heat transfer qualities and doesn't harden like some of the other stuff does.

I think I read somewhere that a guy put too much thermal paste between the CPU and cooler and the CPU got destroyed by overheating because of it.

I usually just put a small drop in the middle of the CPU and spread it into a paper-thin layer using a flexible piece of plastic.

Urban myth.

Maybe. I think I actually heard it on techtv (that channel doesn't exist anymore).

In pictures...

If you look at the thumbnail pictures in this post, you will see what your CPU and CPU cooler surfaces should look like if the cooler heatsink was properly installed. The seal is tight and there is not much paste between the two pieces.

http://www.linuxquestions.org/questi...light=heatsink

"Arctic Cooling Thermal Compound is recommended by two out of three Radical Overclockers" and their CPU and GPU coolers are good too.

Hello people, thanks a lot for your answers and recommendations. Basically what I did when reinstalling the cpu and heatsink was cleaning all the old compound from them with a Qtip drown in a 70% alcohol solution (not excessively drown, of course). After having cleaned completely the old compund, I rubbed a dry Qtip on both, the cpu and the heatsink, and let them get dry long enough (I did the whole process with the heatsink first, then repeated it with the cpu). Then, placed the cpu in its socket and locked the holding mechanism (the plate and the lever). After the cpu was in its socket, I applied the thermal paste (I think this is probably where I failed, since I put the equivalent to two rice grains, maybe a bit less), spreaded it with a clean, thin plastic bag, until the layer of paste was like half a milimeter thin. I also applied thermal paste to the heatsink but in a smaller amount... After reading what you people say, I think I definitely put too much thermal paste in it :doh: ... Gonna try the method suggested by TexMex, but are you sure applying it only to the heatsink will be enough?

As for the temperature readings, I also trust the BIOS readings more than anything else, but I think 47 ºC is a bit hot in normal conditions, mostly considering being in the BIOS must not be cpu intensive, I guess (too bad I didn't check the cpu temps before going to the whole process of replacing the motherboard :( ). A datasheet I downloaded from intel says a maximum case temperature of 61.4 ºC, but I'm not sure about it.

Well, I'm going to try it again and let you know. Also, I bought an extra fan to put at the back of the chassis, so let's see how it goes now.

Greetings!

If you don't pull off the tape, the CPU doesn't even survive 5 seconds under power. I can tell you from experience. (I have built hundreds of PC's, I can't image why I did this stupid act.)

How is CPU temperature measured nowadays? Still with a sensor on the MB which is mounted under the CPU? Or does the CPU have a built-in sensor on-chip which can be read out with a special instruction?

If the sensor is still on the MB, this could be a simple measurement error.

jlinkels

You shouldn't let the paste dry either, just put a small drop on the heat sink and lock it down over the mobo, that's it, no drying no smearing, etc. It's recommended to use 99% isopropanol because 70% contains 30% water, that can damage components ... but if you're careful you might get away with it.

I always apply it to the CPU only (but heatsink only shouldn't make any difference).

To clean off old paste I used cotton balls lightly soaked in rubbing alcohol (all I have).

Hi again folks, sorry for the delay, I was a bit busy the last few days (when I wasn't trying to fix the cpu issue :D).
Well, as I said before, I tried several times in these 4 days (I think I must have repeated the process of setting the cpu and heatsink like 8 times at least). I kept getting high temperatures no matter which method I used to apply the thermal grease (sometimes the temps were higher than others). Then I realized one of the fasteners which attach the heatsink to the motherboard was not adjusting properly, even if it seemed to lock down as it's supposed to do; so I changed the heatsink position and tried again locking this fastener first, and this time all the fasteners adjusted completely tight to the mobo. Now the temperature is about 4 or 5 degrees less when idle; an average of 42 ºC being in the BIOS, and even the OCTuner application (on windows) shows about 37 ºC when idle, which is a real achievement considering the temperatures I had before (some people on other forums report having temperatures above 40 ºC when idle using this cpu, so this may be "normal"). Also, my room temperature is about 27 ºC or 28 ºC in average and sometimes more, so this could have an effect in the cpu temperature, I guess.
I'm not completely satisfied yet, so I will be checking the temps closely in the next days to see how it goes. I'm also thinking about taking out the heatsink (again) to check if the thermal grease spreaded fine this time, since it didn't spread completely before, when I applied it to the heatsink only (due to the fact the heatsink was not adjusting fine). I guess this time it did spread fine since I'm having better results, but I want to be completely sure. I will keep you informed about any issue that may appear :)

Greetings folks, and thanks a lot for your help!

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Alright, just remember that every time you take the heat sink of you should remove the old paste and apply new paste. I would leave it as it is, there's no reason to remove the heat sink to check how the paste spread out, if you put the right amount on there then it obviously spread out as it is supposed to.