Question CPU cores different temps

Feb 25, 2019
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Hi, I got a Lenovo y7000 the other day and now after some testing I found out that core 0, 2 and 4's temperatures are 10-15 degrees higher than core 1, 3 and 5 under heavy load. I can't return it as my uncle got it for me in US and I live in Asia. Is there any way I can fix this? Also, core 1, 3, and 5's temp are the same as mentioned in notebookcheck's review but 0,2 and 4 are higher. All help appreciated as I don't know what to do now :(
Thanks
 

Barty1884

Titan
Moderator
In a mobile CPU, that's not surprising.

Which Y7000 variant do you have? I believe there;s an i7-8750H and then an i5 variant too.

You can certainly reapply thermal paste etc, yes.
'Fixing' the heatsink, if a mounting pressure issue is doable - but if it's just a mediocre design to fit into the space available, there's nothing you can do about that.

That being said, for a mobile intel chip running Prime95*, those temps don't sound bad.

*Which version of Prime are you running? You want v26.6 to not have to deal with AVX instruction which will load up the CPU temps beyond a typical workload - unless, of course, your workload is AVX dependent. If they were, you'd know.
 
Reactions: compprob237

CompuTronix

Judicious
Moderator
According to Intel, up to 15° C variance in core temperatures is considered within specs.
jojesa,

I'm very interested in learning where you found this information.

Unless I somehow missed it during my research through Intel's Core i and Core 2 Datasheets dating back to 2006, I'm not aware of any such thermal specification. However, the Datasheets do state that Intel’s specification for Digital Thermal Sensor (DTS) accuracy is +/- 5°C.

Section 5.1.5.2.1 - Digital Thermal Sensor Accuracy (Taccuracy) - "The error associated with DTS measurements will not exceed +/-5°C within the entire operating range."

See page 95 - 8th and 9th Generation Intel® Core™ Processor Families Datasheet, Volume 1 - https://www.intel.com/content/www/us/en/products/docs/processors/core/8th-gen-core-family-datasheet-vol-1.html

This means with all Cores fully and equally loaded with a steady-state 100% TDP workload (such as Prime95 v26.6 Small FFT's), deviations between the highest and lowest Cores should not exceed 10°C.

If the highest sensor is +5°C above nominal while the lowest sensor is -5°C below nominal, then the deviation would be 10°C. If the deviation is instead 15°C, that would put the CPU out of spec by 5°C. Although sensors are factory calibrated, in reality, Core temperatures tend to be more accurate at high temperatures for "Throttle" protection (100°C). But due to calibration issues such as linearity, slope and range, idle temperatures may be less accurate than load temperatures.

Nonetheless, as you point out in your following statement, deviations on processors that have an uneven application of TIM might exceed 10°C by several degrees.

Sometimes the way thermal paste was applied or if the heatsink wasn't tighten properly could increase the temperatures.
The temperatures discrepancy could be related to the CPU internal TIM, in which case there isn't anything you could do....besides returning it.
Respectfully, while your statement in the first sentence is certainly true, the second sentence is not. As the Lenovo y7000 is a laptop, and mobile processors don't have an Integrated Heat Spreader (IHS), the cooler is mounted directly on the Die. Therefore, the only "internal" TIM on that i7-8750H is between the Die and the cooler, which means the laptop should be re-TIM'd under Lenovo's warranty, since it's out of Intel's "Taccuracy" spec.

CT 😎
 
Reactions: Barty1884

Barty1884

Titan
Moderator
Core variance is nothing unusual. 10-15'C is a little high, but not unheard of variance.

What kind of load temps are you seeing overall? Doesn't really matter if some cores (for example) are at 75'c vs 60'C on the others.
 
Hi, I got a Lenovo y7000 the other day and now after some testing I found out that core 0, 2 and 4's temperatures are 10-15 degrees higher than core 1, 3 and 5 under heavy load. I can't return it as my uncle got it for me in US and I live in Asia. Is there any way I can fix this? Also, core 1, 3, and 5's temp are the same as mentioned in notebookcheck's review but 0,2 and 4 are higher. All help appreciated as I don't know what to do now :(
Thanks
According to Intel, up to 15° C variance in core temperatures is considered within specs.
Sometimes the way thermal paste was applied or if the heatsink wasn't tighten properly could increase the temperatures.
The temperatures discrepancy could be related to the CPU internal TIM, in which case there isn't anything you could do....besides returning it.
 
Feb 25, 2019
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Core variance is nothing unusual. 10-15'C is a little high, but not unheard of variance.

What kind of load temps are you seeing overall? Doesn't really matter if some cores (for example) are at 75'c vs 60'C on the others.
I ran prime 95 test and I was hitting 96 :(
 
Feb 25, 2019
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According to Intel, up to 15° C variance in core temperatures is considered within specs.
Sometimes the way thermal paste was applied or if the heatsink wasn't tighten properly could increase the temperatures.
The temperatures discrepancy could be related to the CPU internal TIM, in which case there isn't anything you could do....besides returning it.
Oh man, I can't return it. We don't have y7000 here and I spent a year to find the right laptop and this happens... Can I myself reapply the thermal paste or fix the heatsink?
 
Feb 25, 2019
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It's the i
In a mobile CPU, that's not surprising.

Which Y7000 variant do you have? I believe there;s an i7-8750H and then an i5 variant too.

You can certainly reapply thermal paste etc, yes.
'Fixing' the heatsink, if a mounting pressure issue is doable - but if it's just a mediocre design to fit into the space available, there's nothing you can do about that.

That being said, for a mobile intel chip running Prime95*, those temps don't sound bad.

*Which version of Prime are you running? You want v26.6 to not have to deal with AVX instruction which will load up the CPU temps beyond a typical workload - unless, of course, your workload is AVX dependent. If they were, you'd know.
It is the i7 variant. And I ran version 29.4. Should I run the test with 26.6?
 
Feb 25, 2019
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You can, but if you're hitting 96'C with AVX (which you are with v29.4) then I wouldn't worry about it at all honestly. Temps sound fine.
Okay thanks mate. That's a relief. I shouldn't paste or apply pressure on the heatsink then? I've also undervolted it now to -.110 and I'm getting better temps
 
Feb 25, 2019
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I wouldn't bother at this stage, no. Everything sounds like it's working as intended.
Okay thanks. And I think I should mention this cuz I'm a newbie and don't know much about it if is should be worrying. The clock speeds to down from 3.8 to 2.8 to maintain 81 c temp on the 3 cores that run hottest, others' temp is 69-71, I'm talking about prime 95 test
 
Feb 25, 2019
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The 8750H should be 3.9 turbo on all cores.

You have an i7-8750H, right? And it's only ever topping out at 3.8GHz at best?
Yes for the first few seconds it runs at 3.8 and then it goes down to 3.2 and then 2.8, I assume this is bad.
 
Feb 25, 2019
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Sounds like throttling. Try running the older version of Prime and see if the issue persists.

Also, ensure your BIOS is up to date.
Yup it's the same. After that I ran both furmark and prime95 together, I'm getting 95 max on 3, and other 3 are at 86 max while maintaining 2.7 GHz. The GPU temp is 73. Should I apply a repaste?
 

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