Temperature difference between cores

[idata]

Hi!

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?

[idata]

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?

[idata]

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.

[idata]

Sounds good, and thanks for your comments.

[idata]

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?

[idata]

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.

[idata]

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.

[idata]

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.

[idata]

Hi,

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

Thanks

[idata]

"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.

[idata]

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.

Thanks

Rick S.

[idata]

Sorry,

idle temps are 28, 28, 30, 28 respectively

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

Rick S.

[idata]

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.

[idata]

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.

[idata]

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.

[idata]

"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?"

Well yes, you didn't find it because it does not exist. I assume you are referring to the following statement from my earlier post, let's look at it again, and feel free to compare it to the original post, which is un-edited:

"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."

I'm very surprised that you saw in my statement any reference to a specification that describes a maximum or minimum temperature range between CPU cores. That does not exist in any Intel CPU documentation. I never said it does. I don't understand why you think that I did.

In reality, in contrast to all the talk about processor and core temperatures, and programs that display processor temperature information, there is nothing in a CPU that we would consider a thermometer. All of the temperatures values that are displayed by various programs are calculated, by reading a data value that is a maximum temperature for the CPU, and then reading a "counter" that indicates how many "steps" a thermal sensor is indicating the processor is below that temperature. Intel processor documents only refer to a very few actual temperature specifications. The main specs for 2nd Generation Intel Core Processors (Sandy Bridge CPUs) are Tcase, and Tcontrol, which refers to the entire CPU, not an individual core.

A processor's temperature alone does not tell us that it is operating safely. That determination is much more complicated than reading a single temperature. Among other things, it is also depends on how much electrical power the CPU is using and the amount of heat the CPU cooler is able to disapate from the CPU. If you want to see this information for yourself, see the following document:

http://download.intel.com/design/processor/designex/324644.pdf http://download.intel.com/design/processor/designex/324644.pdf

I suggest reading Table 1-2, and Section 6.

While it is much easier to discuss, understand, and relate to a single CPU or Core temperature, that is only a part of the picture. I use the same CPU temperature monitoring programs that everyone else does, but I don't worry about small changes and variations. I've also seen programs that were just displaying very incorrect temperatures, so I take them all with a grain of silicon.

I'm sorry to mildly rant about this CPU temperature topic, but your post provided an opportunity to do so, thanks for that. This is something that has bothered me for a while now, and frankly I certainly do not completely understand it, because it is far more complex than looking at a single "temperature" value. It's also true that all the PC enthusiast web sites use single temperature values and many times the same temperature monitoring programs we do. I understand that but hope that someday one of them will start expanding their readers horizons.

Regarding your one core that has a differing temperature, how does the pattern or "fingerprint" of the TIM on your Antec cooler's base look when you remove it? There may be a tiny dimple in it's surface just over that core, causing it to cool less efficiently. Can you turn the coolers base either direction to present a different surface to the CPU? This is a long-shot of course. I hate to say it but the cores of my i7-2600k can be identical at idle, although over time the maximum difference in temp between cores is 9 degrees F, the PC running for five hours but no stress testing on the evening I wrote this post.

[idata]

I must have missed the "Nothing" in your first post, and my brain filled in the gap.

I have tried my cooler in 2 different directions, with the same result.

Also, that post didn't really sound like a rant to me.

Thanks for the clarification.

[idata]

Agarwaen, No problem at all, and thanks for your comment.

Others may have other opinions on the CPU and Core temperature situation, but I am just going by the Intel documents. FYI, if you've never used an Intel mother board, the utility program Intel provides for hardware monitoring, called Intel Desktop Utilities (IDU), does not display CPU or Core temperatures. It does show mother board and chipset temperatures, but for the CPU it shows the number of degrees below the maximum CPU temperature.

One reason that is done, IMO, is that all CPUs do not have the same maximum temperature. That is another reason why simply monitoring a temperature does not really inform the user how close they are to that maximum temperature. If we study those Intel documents about CPU thermal characteristics, we also learn that while our CPU may be at a temperature below it's maximum, but it is using an amount of power above the threshold defined by it's TDP graph (which means it's cooling environment is not keeping up with it's needs) then we have exceeded the overall power/temperature characteristics of that device. That is a situation where CPU throttling will activate. In your case I doubt very highly you would ever experience any CPU throttling, since your CPU cooler is a very high performance unit.

Message was edited by: parsec