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Intel® Processors, Tools, and Utilities
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CPU temp vs core temp?

AWegn
Beginner
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Does this still hold true for current intel i7 processors?

Core temps are an approximation of a real temperature derived from the actual

power consumption in the core... while CPU or Tcase is an electrical impedance

reading converted to temperature from a thermal diode circuit in the processor.

Core temps are a function of the Digital Thermal Sensor circuit while CPU

temperature is more an analog based in how much current is passed by the diode.

CPU temp is really the reading that you need to pay attention to... as it

affects the assertion of Prochot# and Thermtrip# .... Core temps are 'unreal'

functions calculated from derivitives of the assumed core power consumption.

CPU temperature (Tcase) is actually callibrated to a real theremometer.

Thank you for any input on this subject.

Andy

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Allan_J_Intel1
Employee
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Thanks for joining the Processor community.

I am trying to understand the context around your question.

At this stage, are you reading this information from online magazines, forums, or any other technical documentation? Would you able to provide links?

Allan.

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AWegn
Beginner
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What I posted above was from a discussion I had years ago on

 

an ASUS support forum.

http://vip.asus.com/forum/view.aspx?id=20100430231755187&board_id=1&model=P6X58D+Premium&page=1&SLanguage=en-us http://vip.asus.com/forum/view.aspx?id=20100430231755187&board_id=1&model=P6X58D+Premium&page=1&SLanguage=en-us

The technical info was gleamed from Intel® Core™ i7 Processor Series Datasheet, Vol. 1

http://download.intel.com/design/processor/datashts/320834.pdf http://download.intel.com/design/processor/datashts/320834.pdf

What I'm getting after is when cooling the CPU what represents

 

the best temp indicator for cooling effectiveness? Should I be concerned the

 

most with CPU temp or core temps? I understand in 4th gen processors. The core

 

temps come from the DTS. The DTS does not output the real core temps but how

 

close each core is to TJmax. The DTS is

 

for thermal protection not absolute temperature. CPU temp is reported by an analog

 

sensor at the center of the chip. To evaluate effectiveness of processor

 

cooling be it air, liquid or other, which is the best indicator. From my

 

understanding TJmax is not a fixed number but can vary for core to core. Also the CPU temp reported by the analog

 

sensor is outputted to the BIOS. The BIOS interprets this signal and by using

 

tables to determine the CPU temp. These tables can be inaccurate. Core temps

 

outputted to 3rd party software like Realtemp or Coretemp are

 

reporting the core temps # degrees Celsius. Are the core temps reported by 3rd

 

party software of any value?

Do I give you enough info to see what I'm after? If I run

 

Intel processor diagnostic tool the only tem it reports is in the output log

 

file. When I ran it today it says my cpu temp is 62 degrees Celsius from max. I

 

assume this is from TJmax?

Thank you for your help in understanding what is of value.

Andy

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Allan_J_Intel1
Employee
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Thanks for the information. I will come back as soon as I get any feedback from our engineering team.

Allan.

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AWegn
Beginner
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Allan could you edit the subject line of the post to CPU temp vs core temp? never mind I got it edited.

thank you

Andy

Any updated info on this post?

bump

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AWegn
Beginner
1,347 Views

bump

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Jose_H_Intel1
Employee
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Andy, the information you are presenting is still accurate.

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AWegn
Beginner
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Thank you Joe!

So the best source to evaluate cooling effectiveness or efficiency is the CPU temperature?

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