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Tcase to Tjunction?

post #1 of 7
Thread Starter 
How much higher should Tjunction be to Tcase. Cuase I heard about 15c and I'm running closer to 10c difference at full load.

I use Nvidia monitor and speedfan (speedfan doesnt measure Tjunction right with vista maybe?) to monitor Tcase and TAT to measure Tjunction.

Any thoughts?
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post #2 of 7
Quote:
Originally Posted by blacklight115 View Post
How much higher should Tjunction be to Tcase. Cuase I heard about 15c and I'm running closer to 10c difference at full load.

I use Nvidia monitor and speedfan (speedfan doesnt measure Tjunction right with vista maybe?) to monitor Tcase and TAT to measure Tjunction.

Any thoughts?
There is no T_junction as you think of it.. T_junction simply means the Max temp for that cpu... You either have a T_junction of 85c or 100c.. If SpeedFan is lower that TAT/CoreTemp then you have a T_junction of 100c..

TAT/Coretemp read the DTS.. DTS is pretty new to cpus and is enbedded in the core.. Speedfan reads DTS under Core0/1.. However speedfan was made with 85c T_junction in mind, so it's usually about 15C lower..

Your question now is 'what do I use to read my temps'

That is a hard question to answer.. Intel states we should read the T_case and they give a max T_case value at their website (about 61C).. Problem is no one knows of any software that reads the T_case.. The newest SpeedFan is suppose to read the T_case under TEMP2, but mine does not..

My advice is to take about 5-7c off of TAT/CoreTemp.. That should be real close to your T_case value.. This comes from my own testing with thermal sensors.. Or use TAT/Coretemp and just stay below 70c with them...

If you are still confused 'pm' me and I will take more time to explain it as it is confusing..
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post #3 of 7
Thread Starter 
Soooo, when I said T_junction I was referring to something I read in a guide. It was a temp guide for c2d's and it looked pretty legit.

Here it is:
http://forumz.tomshardware.com/hardw...ict221745.html

"Some users also may not know that C2D's feature 3 sensors at 2 different temperatures; a single on-die Tcase sensor (between the Cores), and dual Tjunction sensors (one within each Core)."

-That was one statement made by the author.

So your saying he is flat out wrong? (no sarcasm intended, I honestly dont know)

And also, I use NVidia monitor with my mobo, which gives me a cpu temp (tcase I always thought) of whatever. (usually I stay from 50 -55c when OCing)

I also use speedfan to second the cpu (tcase as I thought) temperature, because my speedfan measures the same temps for cpu (tcase?) as the Nvidia monitor.

I also use TAT

However, the speed fan core monitors and TAT core monitors which I both thought were Tjunction temps according to the guide, were always a ways off from eachother.

And, referring to the guide again, the Tjunction measured by the TAT was only about 7-10 degrees higher as opposed to 15c. But, as I read in the guide, when you use orthos the temps go down to a 10c degrees diff from a 15c difference.

Still, my speedfan reads my cores as about 15-23c LOWER than my cpu read in speedfan and Nvidia monitor.

SOOOOOO, my question basically is, (now that I'm all confused over Tcase-junction) what temp monitor do I need to measure Tcase and Tjunction. (mainly Tjunction, if it exists...) Because my tcase temp I am pretty sure is right because both speedfan and Nvidia monitor measure them about the same... but then again the speedfan tjunction monitor is off, so the other may be aswell...... Ahhh I'm all screwed up!

Finally, I read the post saying that TAT is only supposed to be used for mobile processors, and it said use speedfan. But my speedfan reads lower than the cpu tcase temp!!!!!!!

Ah, what to doo...
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post #4 of 7
Thread Starter 
[IMG][/IMG]






Which core 0/1 temp is right? How come some of the vcores are different? Why does coretemp measure the frequency wrong?
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post #5 of 7
Quote:
Originally Posted by MuNcHeR23 View Post
You either have a T_junction of 85c or 100c.. If SpeedFan is lower that TAT/CoreTemp then you have a T_junction of 100c..
My Speedfan shows idle core temps (at 3.0GHz) to each be 29-30C (CPU 35C) while TAT shows 47C for both cores. So...my T_junct oughta be 100C, correct?

Now...a chip with a T_junct of 100C should theoretically overclock better (due to a higher heat tolerance) than a chip with a T_junct value of 85C, right? Another way to phrase it is that a 100C chip is a tougher chip than an 85C T_juct chip...unless I am missing something.

Also...shouldn't there be some variable (or constant) delta between T_junct and T_case? Or are these two values completely unrelated?

I guess what I'm trying to understand is this:

Intel defines T_case as 61.4C, but there is no way to measure this. We can, however, measure T_junct? If we know the T_junct value (100C) and our current T_junct value (core temp via speedfan) then we know how much room we have until we "max" out the thermal capacity of our chip.

So...if 100C (T_junct) is to 61.4C (T_case)....?

Thanks,
Paul
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post #6 of 7
Quote:
Originally Posted by P.Johnston View Post
My Speedfan shows idle core temps (at 3.0GHz) to each be 29-30C (CPU 35C) while TAT shows 47C for both cores. So...my T_junct oughta be 100C, correct?

Now...a chip with a T_junct of 100C should theoretically overclock better (due to a higher heat tolerance) than a chip with a T_junct value of 85C, right? Another way to phrase it is that a 100C chip is a tougher chip than an 85C T_juct chip...unless I am missing something.

Also...shouldn't there be some variable (or constant) delta between T_junct and T_case? Or are these two values completely unrelated?

I guess what I'm trying to understand is this:

Intel defines T_case as 61.4C, but there is no way to measure this. We can, however, measure T_junct? If we know the T_junct value (100C) and our current T_junct value (core temp via speedfan) then we know how much room we have until we "max" out the thermal capacity of our chip.

So...if 100C (T_junct) is to 61.4C (T_case)....?

Thanks,
Paul
T_junction is not a reading we get.. Its the thermal max for the die (from what i understand).. Intel uses a DTS- Digital Thermal Sensor- in the core for temp monitoring... DTS is used for the cpu speed control (throttling) that we disable when we overclock..

This DTS "temp" is figured backwards from how you may think it is.. You actually take your DTS value and subtract it from your T_junction.. DTS is the reading we get from TAT/CoreTemp and Speedfan (under Core0/1)

Your speedfan CPU 35C reading is more than likely your T_case temp.. I am told that Speedfan shows T_case as CPU.. As far as a constant between DTS and T_case I dont think there is one, as Intel tells me they are unrelated....
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post #7 of 7
Quote:
Originally Posted by MuNcHeR23 View Post
T_junction is not a reading we get.. Its the thermal max for the die (from what i understand).. Intel uses a DTS- Digital Thermal Sensor- in the core for temp monitoring... DTS is used for the cpu speed control (throttling) that we disable when we overclock..

This DTS "temp" is figured backwards from how you may think it is.. You actually take your DTS value and subtract it from your T_junction.. DTS is the reading we get from TAT/CoreTemp and Speedfan (under Core0/1)

Your speedfan CPU 35C reading is more than likely your T_case temp.. I am told that Speedfan shows T_case as CPU.. As far as a constant between DTS and T_case I dont think there is one, as Intel tells me they are unrelated....
Okay.

So then we ought to be able to establish an equation, based on your experience and Intel's quoted figures.

TJ - DTS = TC

Although I am not sure you are consistent (not trying to ding you) in your definitions. Does speedfan measure DTS or T_case?

I've pushed my E4300 to 78C (measured in TAT) with no errors/problems, and I believe that Speedfan would have indicated my temp at that point to be between 63 and 67C.

Until somebody logs failure of an E4300 and then correlates that point of failure to Intel's T_case figure of 61.4C, we will have no way of knowing either our true temps or overhead.

I do appreciate your opinion, insight, and expertise, MuNcHeR. I seek here only to raise my questions and push us all to define temperatures for Intel C2Ds and the various programs we use to try and guess our current temps.

-p
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