CoreTemp vs. RealTemp - Page 13 - Overclock.net

Brutuz · 05-28-08

With your CPU, I know that ones with the M0 stepping get a wrong reading from Coretemp, and my CPU does too, Coretemp gets a Tjmax of 85c when its 100c.

But I don't know with the L2 stepping..

opt33 · 05-28-08

Quote:

Originally Posted by zman

How is this possible? If you would use the theta .3-.4 figure for a QX9775 at load (TDP=150W) the difference from core to case would be 45 to 60 degrees! So with the specified Tcase max of 63C the cores would be at 108-123C, which seems quite high for sustained operation (keeping Tcase temp at or slightly below the intel thermal spec).

Or are you instead arguing that the core-Tcase theta value is highly non-linear? At least the thermal conductivity for copper is quite linear in the 0-100C range which would apply here. Of course I can not know which materials Intel is using between the cpu die and the IHS but I seriously doubt that the thermal conductivity is as bad as .3-.4, or as nonlinear as this value at idle would require.

So where does this .3-.4 value come? Intel documents? Someone removed an IHS and measured it?

Personally I have seen a value of .38 quoted for the core-case theta bu unfortunately I have no idea were that came from either.

You can read the documents, there are several hundred at both the intel site and via search engines or work the numbers out with various formulas that intel supplies. And to be honest, until you are willing to spend the time to do that, and really understand it, you are not going to get it. Once you do spend the time reading, you wont ask those questions, in fact you wont need to, you will understand yourself and the math will be easy and obvious.

But for starters, core-case theta is cpu dependent, and very different for quads. Also theta is not thermal conductivity.

But if you think theta is markedly different for E8400...try solving for theta using 105tjmax, and 95tjmax, it will be enlightening.

But most of the math I have already done on xtremesystems in realtemp thread, along with sources.

zman · 05-28-08

Quote:

Originally Posted by opt33

You can read the documents, there are several hundred at both the intel site and via search engines or work the numbers out with various formulas that intel supplies. And to be honest, until you are willing to spend the time to do that, and really understand it, you are not going to get it. Once you do spend the time reading, you wont ask those questions, in fact you wont need to, you will understand yourself and the math will be easy and obvious.

But for starters, core-case theta is cpu dependent, and very different for quads. Also theta is not thermal conductivity.

But if you think theta is markedly different for E8400...try solving for theta using 105tjmax, and 95tjmax, it will be enlightening.

But most of the math I have already done on xtremesystems in realtemp thread, along with sources.

Thanks for the explanation. Sadly still a few questions, bare with me

1) My google-fu is not as good as it should be. If these Intel docs are full of the theta values for different processors, surely you can give one or two links to such documents which list the theta value?

2) If theta is not thermal conductivity then what is it? Surely it must have a definition? Or is it just a "multiplier"?

Edit: Found the answer my self in several Intel documents. Theta j-c is indeed thermal resistance, as per Intel definition and the unit for it is C/W. (I used the wrong term in my previous post, I said conductivity instead of resistance)

3) What about the linearity of theta? Is the same theta value used at load and at idle (for the same processor)? Or do different theta values exist for different thermal output situations?

SickStew · 05-28-08

Real temp = 26C
Core temp = 36C
Real Temp TJ Max = 95
Core Temp TJ Max = 105
Revision = M0

BIOS VID = 1.245
Real Temp VID = 1.075
Core Temp VID = 1.075

A 10C diff i will go with the higher temp just to be safe

**Retrospekt** · 06-05-08

Quote:

Originally Posted by SickStew

Real temp = 26C
Core temp = 36C
Real Temp TJ Max = 95
Core Temp TJ Max = 105
Revision = M0

BIOS VID = 1.245
Real Temp VID = 1.075
Core Temp VID = 1.075

A 10C diff i will go with the higher temp just to be safe

"I'll go with the higher temp just to be safe."

You've gotten the same thing pounded into your head as just about everyone else on this forum. Temperatures are seen as such a critical object, when in fact you are perfectly safe until you throttle. That is why a chip has a threshold. I have an E1200 at 3.0ghz. Although it doesn't NEED 1.5v, it makes clocking and experimenting easier since I don't have to always keep the though of "Should I up the voltage?" in my head.

Most other forums, many with members who have been with computers since just about their invention, will tell you that temperatures and temp monitoring programs are useless. Most of them are incorrect anyway, so why base your overclock and your voltages on something that is probably giving you innacurate information?

braindrain · 07-07-08

Both Coretemp and Realtemp have my TJ max as 85 and both read my temps as the same........

Pwnography · 07-07-08

Quote:

Originally Posted by Retrospekt

"I'll go with the higher temp just to be safe."

You've gotten the same thing pounded into your head as just about everyone else on this forum. Temperatures are seen as such a critical object, when in fact you are perfectly safe until you throttle. That is why a chip has a threshold. I have an E1200 at 3.0ghz. Although it doesn't NEED 1.5v, it makes clocking and experimenting easier since I don't have to always keep the though of "Should I up the voltage?" in my head.

Most other forums, many with members who have been with computers since just about their invention, will tell you that temperatures and temp monitoring programs are useless. Most of them are incorrect anyway, so why base your overclock and your voltages on something that is probably giving you innacurate information?

I may have to agree with you there mate.

If u get different reading its the difference in your TjMax. Mine were 5 apart i got 5c difference. When you set them the same TjMax u get the same Temps.

So unless theres a certain TjMax you should use then Temp monitoring programs are pointless.

dead_j0ker · 08-25-08

sorry to bump an old thread but my e4300 conroe L2........coretemp says 26 idle, realtemp 15 idle it's winter here and no heaters on which is right?

thx

opt33 · 08-25-08

Tjmax is likely 90. Most cpus there will be about a 27-30C difference between Tcase max and Tjmax. Or intel sets Tjmax 5C higher than IHS temp measured at idle. If coretemp is using tjmax 100 for that cpu, there is no cpu that has a 40C difference between Tcase max and tjmax. Below are the knowns.

Processor--power(W)--Tcase max--Casing IR(idle)--Tjmax
E8400-------65---------72.4-----------95-------------100
Q9650-------95---------71.4---------------------------100
Q9000-------95---------71-----------------------------100
QX9650----130---------64.5----------------------------95
QX9770----136---------55.5----------------------------85

dead_j0ker · 08-26-08

so you think in realtemp if I set my tjmax to 90..there the most accurate temps?

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CoreTemp vs. RealTemp

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