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    Temperature difference between cores




      I have Core i7 2600k and i wonder is it normal when temperature difference between cores is about 8-10 C degrees. CPUs core 4 is much cooler than others, according to several programs i have tried. Like Aida64, Real Temp, Core Temp.


      At the moment Aida64 shows like this: Core 1 42C, Core 2 46C, Core 3 40C and Core 4 36C degrees. Should i be worry about this?

        • 1. Re: Temperature difference between cores

          Your core temp difference is normal, you don't have a problem.  Don't forget, each core is basically an individual processor, and they usually operate individually from each other.  A running program will usually use only one or two cores, so all the cores are not running at the same time, so the ones that are in use will be warmer than the ones that aren't.  There are programs and gadgets available that show the amount of usage of each core, when using one you'll see some cores in use at various levels, and others not, including the hyper-threaded virtual cores.


          It is possible that the thermal compound on the CPU cooler is not spread evenly across the top of the CPU, and if that happens to be just above one or more of the cores, you might see a temp difference.  That is very unlikely, given how small the cores are compared to the surface of the CPU, which is designed to spread out the heat from the CPU components.  A poorly mounted CPU cooler could cause this too, but you would see bad CPU temps in general.


          Are you using the stock Intel CPU cooler or something else?

          • 2. Re: Temperature difference between cores

            I use  Noctua NH-U12P SE2 cpu cooler. Yesterday, I changed thermal paste. This time i try to do it like Noctua recommend, put small dot of thermal paste in middle of cpus heat spreader. And it seems to work fine, temps drop generally little bit. Difference is still there, but under heavy load, tested with IntelBurn Test, it is smaller than idle. But thanks a lot for your answer. I can sleep peacefully now.

            • 3. Re: Temperature difference between cores

              Sounds good, and thanks for your comments.

              • 4. Re: Temperature difference between cores

                What if the temperature difference is massive (one core idling in the 70's, while the other are in the 30's)? Could this still be thermal paste? A broken sensor? Or is there a bigger problem?

                • 5. Re: Temperature difference between cores

                  sam,  If that is your situation, then something is not right.  A broken sensor is a possibility.  First, you need to check the mounting of your CPU cooler.  If it is the standard Intel cooler, I would remove it by turning the top part of the four mounting pin assemblies 90 degrees counter-clockwise, and pull them up.  Be sure to turn them 90 degrees clockwise before remounting the cooler.  With the cooler removed, you can check the functioning of the locking pins by pushing down on each of  the locking pin actuators to see if they engage and hold correctly.  You can also check the thermal interface material (TIM) at this time, and see if it is evenly distributed on the CPU and base of the cooler.  You really should clean off the old TIM and reapply it, so you'll need some TIM, but if it looks fine you might get away with reusing it.  If you can check the bottom of your mother board after re-inserting the CPU cooler, verify that the pins are fully engaged, you should hear a clear click sound when you push each of them down.  They should be locked into place in an X pattern, not in a circular pattern.


                  If you have an after-market CPU cooler, checking the pattern or fingerprint of the TIM on the CPU will reveal if it was mounted correctly, and if an appropriate amount of TIM was used.


                  Regarding a faulty sensor, if it constantly reads the same temperature, that indicates it is very likely bad.  You could try re-mounting the CPU by opening the socket lever, very carefully removing the CPU, and also check the socket contacts for bent pins.  One method of checking the pins is using a digital camera and taking a high-res, close up picture of the socket, and then examining it on a PC, zooming in on the picture.  You can also try a different CPU temperature monitoring program and see if the core temps change.

                  • 6. Re: Temperature difference between cores

                    thank you for the advice parsec. I should have mentioned that my computer has been functioning well for 2 months, idling around 30 and reaching 65C under load. Last night I installed and played BFBC2,. which set a record high for my cpu at 75C. This morning I noticed the issue about 10 mins after i had turned on my computer. I am going to proceed with your troubleshooting steps, but please let me know if this sudden temp change is indicative of anything.

                    • 7. Re: Temperature difference between cores

                      Yes it indicates something, simply that you're playing a graphics intensive game, which puts a much greater load on your video/graphics system, which you did not mention.  Do you have a separate graphics card, or do you use onboard graphics on the mother board.  Do you use the standard Intel CPU cooler?  Is your PC one you bought already built, or did you put it together?


                      Assuming you have a separate graphics card, if you had software to monitor its temperature (many free ones exist, it depends what type of card you have) you would notice that it gets much warmer when gaming.  That is normal, but the heat it generates is usually vented into the PC's case.  Since the video card is usually located close to the CPU, the extra heat it creates affects the CPU.  The CPU is also doing extra work during gaming, but most of the work should be done by the video card.  Which makes me curious about what hardware you have, and if you might have built in graphics on your mother board.


                      All the above adds up to higher CPU temperatures.  It would help to know what your PC consists of, if you'd like to let us know.

                      • 8. Re: Temperature difference between cores


                        How many difference of temperature between cores is reason while cpu under full loading?


                        • 9. Re: Temperature difference between cores

                          "How many difference of temperature between cores is reason while cpu under full loading?"


                          I think you are asking what temperature difference should there be between each core when the CPU is under a full load.  From what I have seen with a few Core i7-900 series and Core i7-2000 series CPUs, if all the cores are at 100% usage for at least five to ten seconds, their temperature's should be the same or almost exactly the same.  They might be different different by a few degress C, but probably not more than 5 degrees C at the most.  The temperature sensor of each core may not be exactly the same, so you could see a few degrees difference in temperature.

                          • 10. Re: Temperature difference between cores

                            I just upgraded to a I7-2600k on a ASUS P8P67 Deluxe B3 MB.  I have a Noctua NH-D14 cooler.  Using Prime95 and OCCT I get the same results.  At idle they are all within a few degrees of each other but under load core#2 will always be 10 to 12 degrees hotter.  I have also used MS FSX with the same results.  The processor is running at stock speed, I have a high air flow Cooler Master case and the ambient temps are around 72 to 75.


                            I have used CoreTemp and RealTemp to monitor the temps.  I have reseated the cooler about 7 times total, using both Antec Nano Diamond 7 and Noctura's NT-H1 thermal paste.  I have attempted to use more and then less paste. Results are consistant.


                            Is this a problem?  I do plan to OC this chip to around 4.5G when I feel comfortable with the temps.



                            Rick S.

                            • 11. Re: Temperature difference between cores


                              idle temps are 28, 28, 30, 28 respectively

                              Load high temps are 46, 47, 57, 47.


                              Rick S.

                              • 12. Re: Temperature difference between cores

                                Rick,  It is very difficult to say with certainty whether or not your CPU has a problem, when one core is "reading"  consistently higher in temperature than the others.  When your CPU's thermal throttling due to excessive temperature is activated, that is not based upon the temperature on an individual core, but what it's temperature is when a certain amount of electrical power (Watts) is being used, along with other considerations. It becomes rather complex.   The maximum temperature at maximum power is actually determined individually for a CPU, and based on several variables during manufacture.  My point here is it is not based on individual core temperatures, and if Intel does not consider it significant, IMO neither should we.


                                You may also simply have an incorrect temperature reading on that core, which cannot be repaired.  IMO your only recourse is to ignore it, or attempt to return the CPU and get another that hopefully will display more consistent temperatures.  But the only real difference likely will be you feeling better about it, which I can understand.  I have a socket 775 CPU that apparently reads, according to one CPU temperature monitoring program, 329F.  Obviously impossible, the CPU works fine and I ignore it.


                                If you read Intel's technical documents about your CPU, there is nothing that states that a core temperature that is X degrees higher or lower than the others indicates a problem with the CPU.  Individual core temperatures are not mentioned at all.


                                The temps you listed are quite good, even great if they are truly at a high load.  IMO you have nothing to worry about, but it's all up to you, and the cooperation of your retailer, or Intel.

                                • 13. Re: Temperature difference between cores

                                  Thanks Parsec,I want to OC this chip and the temp bothers me; if I didn't plan to OC I wouldn/t have a problem with it.  I guess I will call Microcenter and see if the will exchange it.  Thier return policy is good and I have had it less than a week.


                                  Rick S.

                                  • 14. Re: Temperature difference between cores

                                    Well, on the same note as the last two posters to ask questions. My i7 2600k is currently (according to RealTemp) at 33/31/38/30 idle. and at load(Prime95) runs 50/49/57/50. Now I have remounted my Antec Kuhler 620 multiple times, and even got drastic enough to order Indigo Xtreme after my AS Ceramique and Antec Diamond 7 didn't bring that core under control. I have looked for the aforementioned specifications that state how core temps should be at least X degrees of each other, and cannot find anything. Does anyone know this number off the top of thier head?


                                    As with Rick I had plans to overclock this chip, So I think an RMA would be in order if this is not within the norm. (even though I'll lose my $15 TIM)


                                    Thanks for the knowledge.

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