Correct Tj max for cpu's ?

[C64]

Looking for a list or guide for intel cpu's tj max.

Everywhere I look someone says something different for example toms hardware says the 6420 is 70c tj max which is impossible if I set it to that I am getting 16c idle temps which is obviously wrong.

Other sites and people say the 6420 should be 100c and I don't think that could be right either as I am idling at 45c under a tuniq tower and Mx-3 with stock voltage speed step on so 6x multi 2.4ghz so idle at 45c sounds wrong to me.

Is 85c the correct tj max for this chip ? has anyone ever tested using thermal probes to try and figure out the correct settings ?

All this time I presumed 85c was correct for e6*** series.

 

[Philtor]

The first problem is that TJMax is not a clearly defined value. Intel released a lot of information last year but they now refer to this data as TJ Target. Actual TJMax for any processor can either be equal to TJ Target or in some cases it might be slightly higher than the Intel listed TJ Target. Unfortunately, Intel did not provide the user community with any information about how much TJMax tends to vary. Based on my testing and reports from users, a 5C difference doesn't seem too unusual with 65nm and TJMax might vary by 10C in the 45nm CPUs. The result is that two CPUs with the exact same model number might have different TJMax values and it also seems that there are situations where cores on the same CPU can have different TJMax values. For the 45nm processors, TJ Target and TJ Max seem to be similar but for the older 65nm CPUs, actual TJ Max can be 10C or higher for many processors.

This may explain why you can't find a definite answer

 

[C64]

Indeed so in truth nobody really knows if the temps we see under various T junction max settings in temperature readers could be as much as -15c out ?

Maybe taking room temp with side of case off then adding 10c for an idle temp is a way to work it out ?

 

[Philtor]

I don't think the thermal diodes are very accurate at normal temps to be honest as they are calibrated to throttle the CPU or shutdown the system at a given temperature range and for this they are very accurate. I just use HWMonitor but if your using Real Temp then it tends to be more accurate if you set the TJ max setting to 95. Core Temp is usually a couple of degrees above the actual temp.

 

[Voxination]

From what I understood the thermal values get a lot closer to accurate (in relation to TJMax) the hotter the CPU is, for instance (All figures randomly chosen to give example btw) if you idle at say 25C, that reading could be +/- 15C of the actual reading, however the same chip nearer 60C would only be roughly +/- 7C due to it being closer to the TJMax. The theory is when the chip hits TJMax, it is perfectly accurate, as this is what it was designed for, as philtorrens says, to just detect when to throttle the chip.


(Note that the above is all secondary information I read a while back from another forum, so take it with a pinch of salt, all values are estimated.)



I also remember reading about TJMax for 65nm quads being 90C, so that's what I have mine set to, then I simply set my personal limit at 75C (So TJMax -15C) and don't let it go any higher. There could be some flaw to the logic considering I'm idling at ~27C at 3.6Ghz with 1.45v, which seems like a rather low reading temperature wise for the voltage and clock that the chip is at (Under a TRUE btw), however I'm just sticking to not letting it come any higher than -15C to the TJMax.

 

[Guest2]

I have my old X2 3800+ cpu at 100c Tj Max and the temperature reached 97c once. Im sure if it was that temperature really it would have switched off or just stopped working