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10C temperature difference between cores?

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March 16, 2010 7:21:04 PM

Hi folks,

I have an Intel Q9300 2.5GHz over-clocked to 3GHz on stock voltage, liquid cooling.

My CPU temps seem ok - 23C idle up to about 40C under full load, but my core temps are very strange: Core 1 is around 38-42C, Core 2 is 40-43, but core 3 and core 4 are around 50-55C (!). Especially Core 4 easily goes to 54 at idle and up to 73C under load. :o 

Is this normal? I know core temperatures vary, but 10+C seems excessive... :??: 

Could it be I messed up when I applied thermal paste to the CPU? I'm worried I may have been a bit too generous with my AS5 which I've heard can actually have a detrimental effect on cooling...

Any advise would be appreciated! :) 
a b à CPUs
March 16, 2010 7:56:21 PM

3 or 4C (at the same load) is normal. 10C not at all. Be sure that the heatsink has a good contact with the micro. It seems that one side of the heatsink is not making contact. Remove it and turn it to placing.
Another option is that the surface of the heatsink is not smooth enough. That is a bigger problem.
March 16, 2010 8:13:42 PM

Thanks for that! I was afraid this was the case :( 


Do you think it's urgently dangerous at this level?

I've ordered some new thermal paste (IC diamond 7 carat) to replace my Arctic Silver 5 and it should be here day after tomorrow.

Am I running a scary risk waiting 48 hours? The CPU will be mostly idle till then and set the clock back to stock speed as well (I mostly use it to surf the web these days). I'd rather not go through the trouble of resetting the cooler twice in a week, if it's not gonna burn out my CPU...
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a b à CPUs
March 16, 2010 8:22:38 PM

I don´t think is urgently dangerous if you take care and the cpu is not very often at full load. Anyway, I would put back the overclocking for that 2 days.
March 16, 2010 8:40:23 PM

I've just done that - thanks! I might upgrade the radiator fans as well if re-mounting the cooler doesn't make enough difference...
March 17, 2010 11:34:47 PM

Well, I took everything apart, put it back together again - replacing the AS5 with IC Diamond 7 Carat paste, which is supposed to be better and ...nothing.
With the CPU overclocked again, Well temperature temp (from the MB sensor) dropped to 21C idle and 44C under Prime95 (in-place fft tests).

The core temps are about the same under idle - 36,38,49,50C and under load I get 60,59,65,68.

I'm pretty sure I set things up right this time, so I'm inclined to think just I got a weird CPU and leave it at that, unless if one of you has some different ideas to offer:) 
a b à CPUs
March 18, 2010 11:33:07 AM

Sometimes the surface of the heatsink is not totally flat, maybe that is the problem. I would check it.
Anyway, the temperatures that you are getting are taken at the same load, aren´t they?. Because is very usual that some cores are working harder than the other cores.
And yes, other option is that there is a problem with the cpu, but is very strange.
March 28, 2010 8:57:49 AM

It turns out the 10c difference between cores is not so unusual. I re-mounted the cooler and applied better quality paste (IC diamond 7 carat) and the results improved but the 10C difference stayed!

However under load the difference drops to about 5-6C and other people are reporting that similar things have happened. It seems that a few chips just act this way, so I'm not worried about it anymore!

Thanks!

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a c 172 à CPUs
March 28, 2010 12:05:09 PM
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The C2Q's are actually two C2D'd glued together in one package. You would see this kind of difference if the thermal characteristics of the two dies did not exactly match.

Load temps of my Q9950 is 58 - 61 C. Load temps of my Q6600 is 61 - 66 C.
March 28, 2010 2:32:46 PM

it is not unusual at all. your cpu is a quad core.. watch that always the temp of the 1st core will be above the temp of the other cores. i have a q9550 and it happens to me also. don't be afraid at all. simply the core with the higher temp processes more data at the time of the high temp.

my cpu can have a difference of 10 c or even greater.it depends on the cpu core load.
April 4, 2010 12:37:17 AM

Best answer selected by dimitrik.
June 5, 2010 7:09:28 PM

Same thing happens to me.I've just got a new NOCTUA SE2 and I get the same difference I've got with the stock cooler.Exactly the same difference.I don't think it's a problem.I think some cores work harder that's why they get so hot.Or the sensors don't indicate the right temp. for some cores.
!