# General question about cpu temps....



## BigA12989 (Nov 5, 2005)

Well, I'm pretty new to overclocking so I apologize if this is a dumb question, but I'm a bit confused about temperature readings for my CPU. To begin, I have a QX6700 @ 2.67Ghz per core (stock). Now, according to the Intel website, the maximum value for Tcase is 65C. What is confusing me is that the programs I'm using, namely coretemp and realtemp, give me a Tjunction Max of 100C and 85C, respectively. First off, why is there such a large difference between these two readings? Secondly, if what I've been reading is relatively accurate, then my Tjunction temps should be about 10C higher than my Tcase temps, so therefore shouldn't the Tjunction Max be around 75C and not 100C or 85C? 
And just as a note, I for some reason can't get a reading for Tcase using Speedfan. I don't know why, I suppose there isn't a sensor in place or the program simply isn't recognizing it, so the 10C difference between Tcase and Tjunction was just an estimate as I can't actually get any readings myself.


----------



## Underclocker (Aug 13, 2007)

Tjunction max is the temperature at which the CPU shuts itself down to prevent damage from overheating. Your Tjunction temperature is complete different from the max, it's the current temperature of the CPU cores. Tcase (temperature of the case) doesn't always have to be exactly 10C less than Tjunction as a well ventilated case should provide lower temperatures.

Also check out this if you're interested: http://www.alcpu.com/CoreTemp/howitworks.html


----------



## BigA12989 (Nov 5, 2005)

Well I read that and hadn't realized the programs auto-detect the Tjmax based on the kind of processor you have. But If the programs auto-detect Tjmax then why does core temp give 100C while real temp gives 85C?


----------



## seriously (May 14, 2007)

temp programs only auto detect processor type but not the tjmax value. tjmax for desktop processors are not disclosed by intel so nobody know for sure. they only use educated guesses to work out the tjmax value of each processor.

and coretemp author think the tjmax of your processor should be 100c but real temp think it's 85c, period.

so who is right? your guess is as good as mine  possibly both are wrong..........


----------



## Meenakshi (Nov 26, 2008)

what is RAM


----------



## Meenakshi (Nov 26, 2008)

What is the method of taking back up in LAN network


----------



## Kalim (Nov 24, 2006)

seriously said:


> so who is right? your guess is as good as mine  possibly both are wrong..........


Listen to the developer of RealTemp himself here:


> This is good news to finally know a number but this only applies to 45nm and there's still one big problem. Using TjMax=100C for my E8400 means that the sensor error is approximately 20C at low idle temperatures.
> 
> Does using the correct TjMax get us closer to reality? There is a huge amount of error in these sensors at the temperatures where most users use them. CoreTemp and Everest use a linear model but Intel has stated that model doesn't apply to these sensors and they haven't given us any model that does work in that presentation.
> 
> So CoreTemp is wrong, Everest is wrong and SpeedFan is wrong and RealTemp is wrong too. RealTemp realized that there was a problem with these sensors being non-linear and made an attempt to correct for that but it wasn't using the correct TjMax on a lot of processors so it's interpretation isn't much better than the other guys. There are no winners here and none of us are any closer to knowing our real core temperature because the amount of error at low temperatures is huge.


What he is saying is, the temperature measurements shown by internal-core sensors, external-die sensors and motherboard HWMonitor sensors do not match or correlate whatsoever no matter which way you look at it so not one can be taken as the real temperature of the internal CPU.

However, these are Desktop laymen speculating. Intel officially and Intel engineers advising corporations like ours advise and set the system up to make use of *not* core temperatures but CPU temperature given by the BIOS. They state to not trust anything but this value to critical customers for 2.5 years now. Their caution and advice is obviously holding upwards of 95% more merit that the conjectures of any random online person.

Core Temp and Everest developers have been working with Intel for a long time and base their judgments on Intel information while RealTemp developer only arrived in the period after Intel 45nm release and does not work with Intel but uses his own opinions for his tool development. That makes his tool far less reliable or credible than that of every other industry developer working with Intel who oppose the values he uses in his tool. The only period where it will count as reliable is when he uses officially known TJMax values without playing with them any more.

Intel did not publicly reveal TJMax figures for the Intel Core 2 65nm processors but it is common knowledge that TJMax decreases as TDP rises and is based on the CPU TDP. 85 - 95 degrees centigrade is what will most likely be the TJMax for the Intel QX6700 processors.

The TJunction to TCase correlation has not been found valid by end customer experimentation so they have abandoned them. Every testing has so far shown that TCase is linear while TJunction is not linear.

For that specific processor, staying below 55 - 60 C (TCase) is a must under any condition and it does run very hot.


----------



## Valdeam (Nov 24, 2008)

Kalim said:


> Listen to the developer of RealTemp himself here:
> 
> 
> What he is saying is, the temperature measurements shown by internal-core sensors, external-die sensors and motherboard HWMonitor sensors do not match or correlate whatsoever no matter which way you look at it so not one can be taken as the real temperature of the internal CPU.
> ...


Damn. Good to know. Where did you get this info?

Valdeam


----------

