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Q6600 G0 TJmax, which one is right?

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December 14, 2008 2:03:04 PM

Ok I have been trying to find the right TJmax setting of the Q6600 G0 stepping but I just cant find a right one. Some people say 100C, intel says 90C, real temp says it's 95C. Now I'd generally believe intel if I wasnt getting 20C idle on one core in a 19C-20C room. TJmax of 95C and 100C seem more reasonable idle temperatures.

So my question is, is 90C the real TJmax? If not, which one is right?

More about : q6600 tjmax

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December 14, 2008 2:11:39 PM

100c for the go q6600, the b3 is 10c less at 90c.

I'm personally done using core temps as my temperature reading, just fed up with everything changing all the time. I use distance to tjmax in real temp. No matter what tjunction you set, distance to tjunction max will always be the same. I say keep the distance to tjunction max at or higher than 30c and enjoy.
December 14, 2008 2:58:04 PM

Thanks for your answer. It's so annoying that intel is silent about stuff like this...
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December 14, 2008 3:08:34 PM

The single best source of current Tjunction Max information available anywhere on the internet can be found on the Real Temp thread over at XtremeSystems - http://www.xtremesystems.org/forums/showthread.php?t=17... - Since Intel's most recent Developers Forum (IDF) in October, the author of Real Temp, Kevin Glynn, (unclewebb), has changed Tjunction Max in Real Temp Beta releases to 100c for the Q6600 G0, according to Intel's updated Tjunction Max values for 65nm processors. Based upon my own research, as well as Kevin's, and the extremely well informed user, rge, we think that the actual Tjunction Max value for the majority of Q6600's fall between 95c and 100c.

Intel has stated that the DTS sensors are designed for Throttling and Shutdown protection, are more accurate at very high temperatures, become unreliable below 50c, and should be disregarded at Idle. Intel has also stated that Tjunction Max values vary between individual cores, and have a "range" or target value that can be as much as +/- 10c due to variables such as sensor "slope" error, which is especially pronounced on 45nm parts. This highlights the reason why Tjunction Max Values are rounded to the nearest 5c, such as 85c or 100c, while Tcase Max values are instead precise numbers to the tenths of a degree, such as the Q6600 B3 at 62.2c - http://processorfinder.intel.com/details.aspx?sSpec=SL9...

Since everyone is so brainwashed on Core temperatures (Tjunction), they forget that there's a CPU temperature (Tcase)sensor designed for measuring temperatures from Idle thru Load, which is more accurate (when calibrated) than the often sloppy Tjunction sensors. Further, most users are not aware that the temperature shown in Intel's Processor Spec Finder is Tcase (CPU temperature), not Tjunction (Core temperature). Additionally, there's a known and constant relationship between Tcase and Tjunction at Load, which is 5c, and is shown on page 4, figure 5 of the following Intel document - http://arxiv.org/ftp/arxiv/papers/0709/0709.1861.pdf

This provides us with a simple 2 part procedure to accurately calibrate Tjunction Max values for each of your particular processor Cores. By using a standardized test setup and simple elementary school math, step 1 is to measure ambient temperature, then factor known Idle power dissipation values with CPU cooler efficiency values, which gives accurate Tcase (CPU temperature) for Idle calibration. By using the same standardized test setup, step 2 is to run Prime95 Small FFT's then add 5c to Tjunction (Core temperature) for accurate Load calibration.

It's just this simple:

Part 1: Ambient + Idle Power + Cooler Efficiency = Tcase Idle (CPU temperature)
Part 2: Tcase Load + 5c = Tjunction Load (Core Temperatures)

This is the calibration procedure in Section 9 of the Core 2 Quad and Duo Temperature Guide - http://www.tomshardware.com/forum/221745-29-core-quad-t...

When calibrated, your Tjunction Max will typically average about 97 to 98c, which is reasonable and in keeping with Intel's most recent statements concerning the confusion about Tjunction Max values. I developed the calibration procedure early this year before Real Temp was first released. My calibration procedure works, and is more accurate than just relying on uncalibrated sensors using Intel's default Tjunction Max values.

Comp :sol: 
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December 14, 2008 4:09:49 PM

What he said^^^^
December 14, 2008 4:44:33 PM

sportsfanboy said:
100c for the go q6600, the b3 is 10c less at 90c.

I'm personally done using core temps as my temperature reading, just fed up with everything changing all the time. I use distance to tjmax in real temp. No matter what tjunction you set, distance to tjunction max will always be the same. I say keep the distance to tjunction max at or higher than 30c and enjoy.


I agree.. switch to distance to tjmax and you have the real thing..
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December 14, 2008 4:48:38 PM

Not necessarily. Although distance to Tjunction Max is not an absolute temperature, it still involves Tjunction Max. You can still accurately calibrate Tjunction (Core Temperature).

Read my post above. If it's too much for you, then just use the "Easy Button" and rely on uncalibrated sensors and Intel's default Tjunction Max values.
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December 14, 2008 4:59:30 PM

Easy Button... What a great concept, I need one of those :kaola: 
December 14, 2008 5:10:06 PM

I was going to respond to the OP until I saw Comp posted.

Nothing to add here move along. ;) 
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December 14, 2008 5:13:29 PM

Thanks, Tom. :) 
December 14, 2008 5:14:55 PM

sportsfanboy said:
I'm personally done using core temps as my temperature reading, just fed up with everything changing all the time. I use distance to tjmax in real temp. No matter what tjunction you set, distance to tjunction max will always be the same. I say keep the distance to tjunction max at or higher than 30c and enjoy.

soark said:
I agree.. switch to distance to tjmax and you have the real thing..

CompuTronix said:
Not necessarily. Although distance to Tjunction Max is not an absolute temperature, it still involves Tjunction Max. You can still accurately calibrate Tjunction (Core Temperature).
That was a funny post, wasn't it.

Apparently they don't understand that core temp = Tjmax - distance to Tjmax. :lol: 
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December 14, 2008 5:21:30 PM

I'd be happy if I could just get everyone to understand that the temperature shown in Intel's Processor Spec Finder is CPU temperature not Core temperature, and that Core temperature is 5c higher.

I'd be even happier if Tom's would clearly label the Sticky's with a "Sticky" note icon with the word "Sticky" on it like it used to be a few years ago.
December 14, 2008 5:29:05 PM

They won't read it anyway. I told someone to read it and they said it was too much like work.

Everyone wants a shortcut, sad isn't it.
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December 14, 2008 5:33:55 PM

"Easy Button"
December 14, 2008 5:39:08 PM

Yup :lol: 
December 14, 2008 6:54:44 PM

Very informative post. :)  Explained a bit. Regarding Tcase I do not know what is wrong with the Tcase sensor of my Q6600, in everest ultimate it reads 22C with a room temperature of 20C. I doubt that is right. At load it is around 45C.
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December 14, 2008 7:05:50 PM

There's nothing wrong with your Tcase sensor except that it needs to be calibrated. It's at least a few degrees low. Please read the Temp Guide Sticky and calibrate your temperatures. Use the link in my signature.
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December 15, 2008 2:55:45 AM

Zorg

I fully understand what tjuction is as well as tcase, distance to tjunction max and so on. The point I was trying to make was, using the core temperatures as a reading is pointless, as everyone has really been trying to figure that out since core2 came out. I personally have change my tjunction max setting 3 times (I have a b3 q6600). So I was saying, use distance to tjunction max and no more worrying about setting the proper tjunction max.

Of coarse CompuTronix way is the best....However, if your like me and getting close is enough, or you don't have a way to accurately measure ambient temperatures in the computer room, or simply don't care to go through the process, than distance to tjunction max is a good alternative.
December 15, 2008 3:17:53 PM

[Edited]

The big concern is exceeding the Tcase at high Tjunction numbers. The CPU won't throttle or shut down but damage or failure could still occur.

If the distance to Tjmax looks like a good number it may not be. Lets say that a distance to Tjmax of 15C looks good for example. That puts you at 82C given a Tjmax of 97C. Assuming a 7C load offset that will put the Tcase at 74c min. The Q6600 has a Tcase Max 71c.

So even though you are 15C away from a "damaging temp", which on it's face looks good, you are still exceeding the Tcase specification.
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December 15, 2008 4:42:22 PM

I know what your saying... I read on the Xtreme forums about using 30c or higher for distance to tjunction max, which is what I recommended to the OP. UncleWeb even agreed with it, so....

In just about every case if not all cases, a distance to tjunction max of 30+ Celsius is safe.

Also define damaging temp... None know for sure if running the chips that hot damages them. Again on the Xtreme real temp thread, UncleWeb ,RGE, others that work with him, have said why why would Intel set the throttling point so high if they thought it would harm the chip. UncleWeb also wrote " run your chip as hot as you want as long as your computer runs great". I'm not saying UncleWeb is the all knowing computer Genie, but he seems to know quite a bit about this stuff.

That being said, I still prefer to take a more cautious road, so I use 30+ distance to tjuntion max, as I'm no longer obsessed with my core temps, I just want to keep them within reason.
December 15, 2008 5:59:18 PM

That's like saying why would ATI allow the fans to run so slow that their cards run extremely hot if it damages them. If a chip fails prematurely due to increased electromigration it is not their concern, as long as it is not in warranty, which excludes all OCing. Come to think of it, that still doesn't explain ATIs insanely low fan speeds. They don't want their chips throttling prematurely because they would catch grief. Additionally the prochot# and thermtrip# are there to protect the CPU from catastrophic failure, not necessarily to be used as a ceiling to be operated just underneath. If you hit prochot# for a short time and fix the problem, you will probably be fine. If you OC, crank up the Vcore and sit just below the prochot# you more than likely won't. I don't think that Intel ever expects Tjmax to be reached under normal operating conditions, let alone for sustained periods of time.

In either case, I wasn't saying that you should be obsessed with the core temp especially if you are 30+ south of Tjmax. I was just saying that using distance to Tjmax as a rule of thumb for someone that doesn't have a handle on the relative values could lead to trouble. And that does not take DTS errors into account, which can only be addressed by the calibrations in Comps guide.

Reworking the numbers using the "run it unless it throttles" approach we get Q6600 Tjmax ~97 - distance to Tjmax of 2C - 7C max Tcase to Tjmax load offset = a Tcase of 90C. Running a Tcase of 90C for extended periods of time with a Tcase max of 71C specification from Intel is probably a very bad idea. And will probably also result in catastrophic failure.

Maybe someone with some spare chips should run a test and put the issue to bed. I would like to know how long one would last myself.

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December 15, 2008 8:42:37 PM

I hear you Zorg and your right... I never said chips should be run near their tjunction maxes. I also agree that high temps usually go together with high voltage, where electromigration can be a problem.

What I have been reading on the Realtemp thread has made me rethink the over all importance of temperatures. Uncleweb pretty much said that you are safe to run your chip as hot as you want as long as it's stable. That were his words not mine. So I used the logic that a modern Intel chip should be able to run up to what Intel says is max temperature, for the length of the processor warranty. I mean think about it... If Intel says max tcase is 62c, and you run it around that hot, and it dies, can't you use the warranty? I think you should be able to. Every one goes by Intel's max voltage numbers, so why is the temperature any different?

Unclewebb has brought just about every processor he has to within a couple degrees of tjunction max and they haven't died yet. But I don't know how long he test them and if there was any damage. I'm sure he will post if that happens.
December 15, 2008 9:04:28 PM

I want to keep my chip longer than the warranty period, plus I really have no warranty due to my OC. I would like to see a long term test at Tjmax though. It would be interesting to see how they fare.
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December 15, 2008 9:47:36 PM

That would be interesting, it would give us an idea of how hard we can actually push these chips.

It is weird that Intel would specify a particular tcase max, then release documents that give tjunction max. When it's now clear that if you do reach tjunction max (which according to them is a safety feature that triggers "throttling"), you would be well over the specified tcase max. Do they do this s--t on purpose, lol.

Maybe I'll post something similar in the Realtemp thread and see what feedback I get.

December 15, 2008 10:38:05 PM

Let me know what you find out.
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December 15, 2008 11:17:45 PM

I posted the paragraphs below in the Realtemp forum, I'll post back when I get some info.


I have a couple/few question that I hope you guys can answer for me. I'm wondering why Intel states that for my chip (b3 q6600) tcase max temperature is 62c. Then they release info saying that tjunction max is (excuse me I don't remember exactly what it was) around 80c. Doesn't that mean by reaching their specified tjunction max, we would be by a large margin, over their specified tcase temperature? Seems like a contradiction, or just messed up info to me.

Also I have been debating with the people over at Tom's Hardware about operation temperatures and their relationship with the life expectancy of the processor. If I were to run my q6600 at let's say 80c with a voltage setting of 1.4, is it safe to assume that no damage is occurring provided the voltage stays under max specs? Or should I expect my chip to last about as long as the Intel warranty of three years, or less even?

I'm also curious if any of you have done any prolonged high temperature testing, to see if any damage has been sustained.

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December 16, 2008 4:44:27 AM

Ok this is the reply I got from The author of Realtemp


SportsFanBoy: According to Intel, TCase is measured with a thermocouple attached to the geometric center of the IHS by cutting a groove into the top of your CPU. When you are running an application like Prime95 at full load, the core temperature might be 25C hotter than the TCase temperature. These CPUs dissipate heat that quickly over that small of a distance. Contact rge who did some very interesting testing of this or scroll back about 20 pages or so to find his work. An 80C core temperature would not put your TCase temperature over Intel's rating.

Intel refers to their recent release as TJ Target numbers. A TJ Target number of 80C may translate into an actual TJMax of closer to 90C. The information released by Intel last summer and in the fall didn't really clear this up. The TJ Target numbers do not equal TJ Max for a significant number of 65nm CPUs that they've produced.

I have no idea how much long term heat an Intel CPU can take. I do know that they seem to be able to take far more heat than people would think. Here's an example you can share with your friends over at Tom's. Three hours running Prime95 Small FFTs without the CPU fan turned on definitely created some heat:

http://img204.imageshack.us/img204/276/hote8400fw5.png

If your Q6600 is running stable and not thermal throttling then don't worry about the heat. If Intel thought 80C was too much heat then they'd lower TJMax and prevent their CPUs from ever reaching that temperature. Intel actually did the opposite and raised TJMax as their manufacturing process matured. Heat related warranty / RMA claims must have been a non issue. I've never had a problem even with all of my insane testing.
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December 16, 2008 6:07:04 AM

Using distance to Tj Max is more of an "issue" with Core 2 Quads, or "double cheeseburgers" if you like, than it is on Core 2 Duos.

Tj Max for a quad is often noticeably different between the pairs of core within a double cheeseburger package. If one pair of cores used 95C and the other 100C then the second pair will always appear to run 5C hotter, whether you use distance to Tj Max or absolute temperatures. Assuming near-equal load on all cores, the temperatures should all be very close, not 5C apart. I don't remember if Core i7 is affected by this or not.

Of course, changing Tj Max in Real Temp, Core Temp or any other program isn't going to correct the DTS output, but it will provide more accurate absolute temperatures for the cores who's Tj Max inflates their reported temperature. Then you have slope error to factor in as well.
December 16, 2008 8:16:38 AM

Interesting
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December 16, 2008 8:19:51 AM

Here (the cooldown test) is an example of what I meant. Notice that cores 0/1 and core 2/3 pair up nicely throughout the working range of the sensors.
December 16, 2008 5:15:22 PM

Mine are within 2-3 degrees and I think its the weight of the Ultra 120EX.
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December 16, 2008 9:23:40 PM

It could be, but the difference is quite commonplace and usually in pairs like that. I'd say that a difference in Tj Max is probably playing a part too, since it can vary by so much.
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December 18, 2008 6:27:57 AM

sportsfanboy, Zorg and randomizer,

Allow me to elaborate on unclewebb's reply.

Let's start with Intel's Thermal Specification, as it applies to desktop processors:

"maximum case temperature at the maximum Thermal Design Power (TDP) value ... measured at the geometric center on the topside of the processor integrated heat spreader."

Intel's Thermal and Mechanical Design Guidelines describes in great detail how they cut a precision groove into the integrated heat spreader in their labs, in order to embed a highly accurate thermocouple for controlled temperature testing with the stock heat sinc. This is how they accomplished measuring Tcase Max to the tenths of a degree, such as 62.2c for the Q6600 B3 at 105 Watts. At the same time, the Core temperatures are about 25c higher, which illustrates the considerable thermal gradient between the IHS and the DTS, and explains why users are frequently puzzled as to why their cooler only feels warm to the touch while running Prime95 Samll FFT's.

Tjunction Max is calibrated so that Throttling occurs a few degrees higher than the gradient, so the total gradient between Tcase Max IHS temperature and Tjunction Max is typically about 27 to 28c. This is why Tjunction Max becomes just a rounded or "target" figure to the nearest 5c such as 85c or 100c, due to variables such as DTS accuracy, calibration deviations, and sensor "slope error". rge was recently able to duplicate Intel's lab tests by obtaining the proper type of thermocouples and test equipment, then audaciously drilled holes through the stock heat sincs and integrated heat spreaders of a few sacrificial Core 2 variants. His findings confirmed that the IHS to DTS gradient is as mentioned above, + / - a few degrees.

As the end user has no way to duplicate Intel's lab test setup, and since Intel states that the DTS array was designed for Throttle and Shutdown protection only, we are all instead supposed to be using the Analog Diode CPU temperature, which is designed for accurate temperature monitoring up and down the scale, and is integrated into the CPU package substrate layers, bottom dead center, for this very purpose. This is why motherboard OEM monitoring utilities, which are included on the driver CD, do not feature Core temperature monitoring, as per agreement with Intel.

I've always found that although BIOS is typically miscalibrated by at least a few degrees, the Analog Diode CPU temperature is consistently accurate and linear when calibrated, and I've only once seen one "stick". Since rge was also able to verify that the calibrated Analog Diode CPU temperature is 5c less than the DTS Core temperaure at load, his findings confirm Intel's results shown on page 4, figure 5 in the following document - http://arxiv.org/ftp/arxiv/papers/0709/0709.1861.pdf - with which unclewebb, rge and I are very familiar, and frequently use for reference.

This means that if the Analog Diode CPU temperature is reading 95c, (which is calibrated by BIOS, but we can measure and re-calibrate), then the DTS Core temperature should be about 100c, (which is calibrated by Intel, but we can measure and re-calibrate), so the actual IHS temperature should be about 70c, (which we can't measure). If, for example, we plug in the IHS (Tcase Max) value for the Q6600 G0, then we have the following:

Tcase Max = 71c
Analog Diode = 95c
Tjunction Max = 100c
Tc / Tj Gradient = 29c

When unclewebb began IR testing with the cooler removed from the IHS, he determined that a Tjunction Max of 95c was appropriate, however, I always thought that he was low by perhaps 2 degrees due to minor factors such as the thermal resistance from the hot spots within the cores through the sensor bonding agent and thermal compound under the IHS, to the masking tape he applied to the top of the IHS to supress IR scatter. Over the past 4 months, I've re-tested 65nm variants and re-verified my original findings for the Guide, as well as having conducted new IR testing and analysis using 3 temperature plots instead of 2, in order to conduct a comparison study of "slope error" and calibrations for the following 65nm and 45nm dual and quad variants:

65nm - E2160 L2, E4500 M0, E6600 B2, E6850 G0, Q6600 G0
45nm - E5300 R0, E7200 M0, E8500 C0, Q9650 E0

The abridged results are that I found for a given processor variant, whether dual or quad, and regardless of whether or not Real Temp used, for example, Tjunction Max 95c or 100c, by using the calibration procedure in the Guide for SpeedFan, (Tcase Load + 5c = Tjunction Load), with which I know you're all familiar, I consistently found that Tjunction Max calibrated values were 97c to 98c, which I believe to be highly accurate, and helps to prove just how very close unclewebb was. So just for fudge factor, let's round up my findings to 98c and tweak the numbers:

Tcase Max = 71c
Analog Diode = 93c
Tjunction Max = 98c
Tc / Tj Gradient = 27c

Gradient look familiar? Much of unclewebb's and rge's recent testing shows that Throttling typically begins a few degrees below Tjunction Max, and that common Tc / Tj gradient values are about 27 to 28c. Now, let's summarize this information and put it into perspective.

(A) We have Intel's IHS lab test temperatures which the end user can't duplicate, but are the temperatures shown for Thermal Specifications in the Processor Spec Finder.

(B) We have the Analog Diode CPU temperature which Intel expects us to use.

(C) We have the DTS Core temperature which Intel does not want us to use.

(D) As experienced overclockers, we all know that hot = unstable, so we don't exceed 25c to 30c Distance to Tjunction Max.

You've all seen me preach on numerous Forum threads:
The temperature shown in Intel's Processor Spec Finder for Thermal Specifications is CPU temperature (Tcase), [i said:
not Core Temperature (Tjunction), which is a very common misconception among many users.]The temperature shown in Intel's Processor Spec Finder for Thermal Specifications is CPU temperature (Tcase), not Core Temperature (Tjunction), which is a very common misconception among many users.
[/i]So the contradiction in terminology becomes obvious; contrary to what I show in the Guide, Tcase and Analog Diode CPU temperature are not technically synonymous terms. As I know you all appreciate the complexity of this topic, I thought if I introduced yet another definition and deeper concepts into the Guide, it would become too difficult for all but the most advanced users to understand, and as you're all aware, there's been enough heat :lol:  about it being too complicated as it is. This is why I state right up front:
... certain strict definitions have been relaxed to simplify concepts ... said:
... certain strict definitions have been relaxed to simplify concepts ...
As I'm sure you recall, randomizer, you and I went over this point somewhat recently, and rge and I also discussed the issue several months ago.

Terminology not withstanding, if we apply the "strict definition" of Intel's Thermal Specifications toward a more practical usage, and instead regard Analog Diode CPU temperature in the same context as Tcase IHS temperature, then we maintain the same 25c to 30c Distance to Tjunction Max, we all keep our chips chilled, and the n00bs don't assume that it's OK to run at 100c. If we look at one of the Scales in the Guide, it's clear how well the IHS Thermal Specifications in the Processor Spec Finder translates into sensible temperature scaling, as if Intel intended it to be as such:

Scale 2: Quad
Q9x50: Tcase Max 71c, Stepping E0, TDP 95W, Idle 16W
Q9x50: Tcase Max 71c, Stepping C1, TDP 95W, Idle 16W
Q9400: Tcase Max 71c, Stepping R0, TDP 95W, Idle 16W
Q9300: Tcase Max 71c, Stepping M1, TDP 95W, Idle 16W
Q8x00: Tcase Max 71c, Stepping R0, TDP 95W, Idle 16W
Q8200: Tcase Max 71c, Stepping M1, TDP 95W, Idle 16W
Q6x00: Tcase Max 71c, Stepping G0, TDP 95W, Idle 16W

-Tcase/Tjunction-
--70--/--75--75--75--75-- Hot
--65--/--70--70--70--70-- Warm
--60--/--65--65--65--65-- Safe
--25--/--30--30--30--30-- Cool

Nonetheless, I intentionally don't mention Tjunction Max values for any processor variants anywhere in the Guide, because my calibration procedure for SpeedFan is quite accurate without it, and based upon what we know at this juncture from Intel, Tjunction Max values are still very much in question for many 65nm variants. As always, my goal is to bring a better understanding of this crazy topic to everyone, so if there are any aspects of this discussion that I haven't considered, then please let me know.

Best Regards,

Comp :sol: 
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December 18, 2008 7:40:32 AM

Your posts (er essays ;) ) are appreciated as always.

My B2 E6600 has always been a pain to determine temperatures with, so I generally ignore it now. My only thermometer was recently shattered so I can't measure ambient temperatures and therefore can't calibrate speedfan; but I'm fairly sure that right now TCase (the "relaxed" definition of it) is alot more than Ambient + Z, and without calibration, Tcase load to Tjunction load is 12-13C when using a Tjunction Max of 90C. :na: 
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December 18, 2008 7:46:42 AM

Yeah, rando, Jack's a tough act to follow! :pt1cable: 

I still think that your E6600 is the variant which has high Idle power.

E6x00: Tcase Max 60c, Stepping B2, TDP 65W, Idle 24W (Spec# SL9S)
E6x00: Tcase Max 60c, Stepping B2, TDP 65W, Idle 12W (Spec# SL9Z)

Do you still have the retail box?
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December 18, 2008 11:54:39 PM

Good stuff, thx Comp
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December 19, 2008 12:02:14 AM

CompuTronix said:
Yeah, rando, Jack's a tough act to follow! :pt1cable:  I still think that your E6600 is the variant which has high Idle power.

E6x00: Tcase Max 60c, Stepping B2, TDP 65W, Idle 24W (Spec# SL9S)
E6x00: Tcase Max 60c, Stepping B2, TDP 65W, Idle 12W (Spec# SL9Z)

Do you still have the retail box?

I do not have it no, but I am fairly sure it was an SL9S from memory when I last pulled off the heatsink. Either way, Ambient + Z still ends up too low. And yes, I have reseated my heatsink, too many times IMO ;) 

I sure as hell exceed TCase Max under load :lol:  Last night I was around 64C I believe, while core temperatures were about 75-76C with Prime95 small FFTs with that 90C Tj Max as I mentioned earlier. As unclewebb said in a PM, my E6600 is the only one he's seen that would make Intel's Tj Targets look sort of right :lol: 
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December 19, 2008 12:09:11 AM

Some chips just run hot, and that's that. My b3 quad is a space heater, thank god for winter! I reseated my Tuniq 3 times thinking it was me, because my temps were around 5+ or so degrees hotter than everyone else under similar circumstances. I think you and me got lousy chips randomizer,lol
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December 19, 2008 12:18:40 AM

sportsfanboy said:
I think you and me got lousy chips randomizer

Yea, I just accepted it after a time. It is a pain though, since I need high voltages to overclock nicely and that always trips PROCHOT even in something single-threaded like SuperPi :( 
May 6, 2010 5:56:41 AM

Priv said:
Ok I have been trying to find the right TJmax setting of the Q6600 G0 stepping but I just cant find a right one. Some people say 100C, intel says 90C, real temp says it's 95C. Now I'd generally believe intel if I wasnt getting 20C idle on one core in a 19C-20C room. TJmax of 95C and 100C seem more reasonable idle temperatures.

So my question is, is 90C the real TJmax? If not, which one is right?


What I have learned screening several forums regarding the exact same question:

To make it easy: First of all there are two different types of sensors. One sensor is located at the heat sink and is called Tcase. This sensor is obviously very correct and stable. I found that at room temperature and idle PC (not overclocked) it is very close to the MOBO sensor. At throttle PC (idle and not overclocked) and room temp the Tcase is exact the same as the ambient (room temp measured with an external digital thermometer near the CPU case). Intel provides a “maximum” Tcase value (Thermal specification) for each processor (similar that it provides a Vc max value) (Ref 1). These values should not be exceed otherwise it would affect the processors lifetime. For Q6600 G0 the Tcase “max” is 71C (see Intel spec sheets) and regarded as “hot” (similar Vc 1.55 shall not be exceeded). Intel also mentioned in a paper that 20C above Tcase silicon damage might occur (Ref 1). In the case of Q6600 G0 this would be 91C. This is the same temp at which the CPU will automatically throttle and then shut down (to force down-cooling). There are several programs that provide the read-out of Tcase. My feeling is that this is a good way to monitor CPU heat. For example at idle PC (overclocked, 24C room temp and a zalman-type of fan) my Tcase is 34C (with core temps between 36 and 40). At 100% load (small fft prime time) for 10 min it will reach 56C. Which means I am still 15C far from considered having a hot CPU (71-56 = 15). The distance to Tj max is 28 under this situation which means I am also far from reaching a critical situation. Tj max for Q6600 G0 is published by Intel to be 90C. Which makes sense as this is the temp the CPU will automatically shut down to prevent silicon damage. Even though there is a huge discussion about whether this value makes sense or not. One argument that this value makes sense is that it is close to the published value of Tcase + 20C for almost all CPUs (Ref 1). As Intel also publishes that a core temp (Tjmax – DTS) cannot regarded to be stable below 50C and measurements have shown that it can fluctuate of about +/- 30C at room temp (Ref 1) is it not surprising that when setting a Tj max of 90 we would receive values that might even went negative. Knowing this, a calibration (as suggested by Realtemp) would not make sense and would even increase the error. Setting Tjmax to 90C for a Q6600 G0 would result in my case (at 100% load for 10 min) in temperatures ranging from 63C (core 1 and 2) to 61C (core 3 and 4). This fits quite nicely with the assumption that there is a 7C difference between Tcase and core temp (IR thermometer measurements) using a better cooling fan (zalman etc). Even though I decided to watch my Tcase temps (instead of core temps) I would assume (and this is the only assumption here I make) reaching 78C (core 1 and 2) and 76 (core 3 and4) would be regarded as a hot core temp.
In conclusion, my personal opinion is that there should be a rethinking going on. Everybody is watching Vc and trying not to get it close to the published max value (for example Vc max 1.55). So why not simply watching Tcase and not trying to get it close to the Thermal Specification (71C in my case)?
(Ref1 http://www.overclock.net/intel-cpus/476469-truth-about-...)

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