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The Truth about Temperatures and Voltages

144K views 598 replies 93 participants last post by  lodestar 
#1 ·
This article is based mostly on Intel CPUs. Though the information may carry over to AMD CPUs, I do not claim that any information contained below is true for AMD cpus.

Please use common sense, good cooling, and test stability stringently; and you shouldn't have any problems.

How to Set Your Temperatures Correctly / TJ Max Explained
There has been a lot of speculation recently about temperature readings on the Core 2 line by using different programs or that certain programs are better for 65nm Quads vs. 45nm Quads. The truth of the matter is that all of the programs are just taking a reading given by the motherboard and using a very basic equation to find the reported core temperature.

Core Temp = TJ Max - Distance to TJ Max.

The motherboard reports the distance to TJ Max and the program inputs it with its value for TJ Max (Thermal Junction Maximum). Therefore if the wrong TJ Max is set, all core temperature readings are wrong. The TJ Max Values for most of their processors, but the Distance to TJ Max will always be correct.

Intel Source

Intel Atom N270 --- 90C

Notice: B3/L2/M0 Steppings were not included directly in the pdf sourced above. I never noticed their exclusion from the pdf and their subsequent inclusion by Tom's Hardware from which I took the chart and changed to fix the for update. I have now removed the B3/L2/M0 steppings from the chart with the exception of the L2/M0 E1000 which was in the pdf. Intel has said that it was their goal to raise TJ Max in the GO steppings so one could infer that the B3/L2 steppings would be the same as the B2 steppings, but there is not a definitive word and I will not make assumptions. Also, I would guess that the M0 would be increased like the G0, but again there is no definitive word as these TJ Max Targets were never released.

Update: Reportedly, Core i7 CPUs read their TJ Max settings off of the die, but some programs are not yet patched to the settings encoded into the die. The average TJ Max seems to be 100C for the Core i7 line thus far, but please PM me with a screenshot if your i7 seems to be showing a different TJ Max.

With this knowledge, you should set each temperature monitoring program with the correct TJ Max.

For Real Temp, simply hit settings and in the new tab window hit Set TJ Max so you can set the correct TJ Max for each core.


For Core temp, go to Options/Adjust Offsets and set the offset to the difference between what Core Temp shows and the real TJ Max value. So in my case it showed 100C for my TJ Max, but the real TJ Max for a G0 Q6600 is 90C. So, 90-100= -10 Offset.



For HWMonitor, close HWMonitor and then open hwmonitorw.ini with notepad. Set "CPU_0_TJMAX=" to your TJ Max. (Example: CPU_0_TJMAX=90.0) Save and reopen HWMonitor.

Now all three programs should read the same for each core temperature.


The Other Side of TJ Max
TJ Max is an inherently unreliable and inaccurate method of measuring idle/low temperatures. Due to the way it was designed, the readings are so inaccurate under 50C that Intel says they can only be read as a number temperature below 50C. As the temperature approaches TJ Max, the precision increases and at TJ Max the temperature is considered to be 100% accurate. Because of this error at low temperatures, sub-ambient temperature/very high readings are sometimes given for idle temperatures. With the TJ Max method, your idle temperatures have no accuracy and therefore should be ignored. Under load, the temperatures become much more accurate and should be very carefully monitored.

A good example of the inaccuracy can be shown on the Q6600 (G0) with a TJ Max of 90C. At 90C, it is perfectly accurate, but at 50C is becomes as accurate as plus or minus 10. Below 50C, the error grows even larger to the extent of plus or minus 30. Notice that after TJ Max has been reached nothing can be said about temperatures accuracy or innaccuracy.


The Controversy
The numbers listed above are not the actual TJ Max values for each CPU; they are the TJ Max Target values. Each CPU has its own TJ Max that should be near the values above, but it may not be exact. Each CPU is set individually at the factory, but the TJ Max Target is what they were aiming for so it is the best estimate of what our core temperatures really are.

The argument then says that you should calibrate your TJ Max by measuring the ambient temperature in the room, setting your CPU at stock with stock voltages, but then lower your multiplier to the lowest possible (usually 6 for Core 2 CPUs). Then adjust the TJ Max until your idle temp readings are about 7C higher than ambient. The problem with this argument is that Intel has implied that the Distance to TJ Max values are not linear, and therefore you would have accurate idle temps (not important) and very inaccurate load temps (very important).

The Tj Max Target values may not be exactly right for your chip, but the calibration method also relies on the idea which the Distance to TJ Max is a linear progression, which Intel infers that it is not.

Another problem with calibrating to idle/ambient is that you immediately introduce mass amounts of uncertainty into the readings. The article lists off possible values for temperature readings based on cooling type, but there are many reports of exceptionally "hot batches" of cpus, which would idle much higher than ambient temperature not due to the cooling but the thermal wattage dissipation. By saying that my cpu should idle around 8C higher at stock idle than ambient, I am already guessing at the capabilities of my cooler and at the heat it is dissipating. Depending on the cooler and the chip the uncertainty would just vary too much for my taste (Could be very accurate or could very inaccurate).

More Information and better instructions for the Idle/Ambient Calibration Method

CPU Thermal Specification
**WARNING**This is a very highly debated subject and I must say before I start say that this is your processor and running it at whatever temperature you decide to run it at is your choice. Also, a nice reminder is that lower temperatures mean higher overclocks. If you let your temps go to the maximum, it can actually cause more instability. **WARNING**

A very comprehensive list of voltages and thermal specifications for both AMD and Intel can be found here (Courtesy of DennyB). Something to be noted is that Thermal Specification is not the maximum temperature for the cores; it is the maximum temperature at which the center of the Integrated Heatsink (IHS) should go to.

Quote from Intel

Quote:
Thermal Specification: The thermal specification shown is the maximum case temperature at the maximum Thermal Design Power (TDP) value for that processor. It is measured at the geometric center on the topside of the processor integrated heat spreader. For processors without integrated heat spreaders such as mobile processors, the thermal specification is referred to as the junction temperature (Tj). The maximum junction temperature is defined by an activation of the processor Intel® Thermal Monitor. The Intel Thermal Monitor's automatic mode is used to indicate that the maximum TJ has been reached.
(Courtesy of TwoCables)

On average, the temperature of the heatspreader is about 10-20C lower than that of the cores. This varies from CPU to CPU depending upon solder. So if the thermal specification of a CPU is 71C, the cores would have to be running at 81C before you would reach the thermal specification. Remember though, running up your temperatures that high can and will cause more instability. This is why people almost always achieve higher overclocks on water, DICE, and LN2 respectively; CPUs run better colder.

Another interesting idea is that the thermal specification (Tcase) may increase as the Power increases linearly. In fact for the Q9000 series, T=0.28P+44.8 where T is Temperature in degrees C and P is Power in watts. Source Page 79 This suggests that at higher overclocks the thermal specification of the CPU may be higher than normal, so it may be even harder to hurt your CPU with temps. It has been well documented that CPUs are resilient to heat and can withstand harsh conditions without degrading. Example

Again, higher temperatures cause instability and will lower your maximum overclock.

When will you begin to thermally throttle? **Warning Technical**
You will not begin to throttle because of temps until you are approximately 20C above Thermal Specification. For example, the Thermal Specification (Tcase) of the Q6600 G0 is 71C. At approximately 91C, it will begin to thermally throttle. This then makes sense why the TJ Max target is 90C; Intel is trying to make the sensor the most sensitive when it is at the point of damaging the CPU. TJ Max Target is not the point of damage, but it is close to the THERMTRIP# point (the point when the CPU automatically throttles and shuts down until proper temperatures are restored). Since as discussed earlier thermal specification (Tcase) is actually the temperature of the center of the IHS and it's temperatures are ussually 10C below core temps, there is actually a 10C buffer between Distance to TJ Max=0 and Permanent Silicone Damage. What Intel has done is said that they are not allowing for any difference between the temperature of the cores and the temperature of the IHS and thus we are aligning Tcase (without buffer) with TJ Max. Remember however that depending upon the solder the difference between Tcase and Core temps is ussually 10C, Intel is simply being safe and not allowing for any difference even if it exists.

If you look at most CPUs Tcase values, their TJ Max Targets are almost always 20C above their Thermal Specifications (Tcase) which perfectly matches with this concept.

Intel Technical Quote

Quote:
In the event of a catastrophic cooling failure, the processor will automatically shut down when the silicon has reached a temperature approximately 20°C above the maximum Tc. Assertion of THERMTRIP# (Thermal Trip) indicates the processor junction temperature has reached a level beyond where permanent silicon damage may occur. Upon assertion of THERMTRIP#, the processor will shut off its internal clocks (thus, halting program execution) in an attempt to reduce the processor junction temperature. To protect the processor, its core voltage (VCC) must be removed following the assertion of THERMTRIP#. Driving of the THERMTRIP# signal is enabled within 10 μs of the assertion of PWRGOOD (provided VTT and VCC are asserted) and is disabled on de-assertion of PWRGOOD (if VTT or VCC are not valid, THERMTRIP# may also be disabled). Once activated, THERMTRIP# remains latched until PWRGOOD, VTT or VCC is deasserted. While the de-assertion of the PWRGOOD, VTT or VCC signal will de-assert THERMTRIP#, if the processor's junction temperature remains at or above the trip level, THERMTRIP# will again be asserted within 10 μs of the assertion of PWRGOOD (provided VTT and VCC are valid).
Source Page 72

Example.
The E6600 Thermal Spec is 60.1C and allowing roughly 20C until Silicon damage gave it a Target at 80C. Everyone knows how poorly stock heatsinks perform and if you had a failure, it might not kill the CPU if it could just about boil water before taking damage. Over the years, Intel has refined their craft and on the same architecture size (65nm in this case) they were able to increase the Thermal Specification of the G0 to 71C with a TJ max of 90. It could have also been a change in the fabrication process going from B2 to G0 increasing the maximum operating temperature before damage.

The 45nm fabrication process could have also caused an increase in silicone heat resistance. If you look at the TJ Max Targets for almost all 45nm Intel CPUs, they are all higher which according to that PDF means they can take higher temps.That's not conclusive evidence that Intel is working on making CPUs more durable, but why wouldn't they.

The exception is extreme editions CPUs, which are by most accounts designed for running on extreme cooling. For example, the QX9770 has a thermal specification of only 55.5C! This might be called heresy, but it's very possible that extreme edition CPUs might be designed to run at extreme speeds but are actually made on lower quality silicone/manufactoring process as there is no need to make them stand up to high temps.

What about Maximum Voltages and Overclocking?
If you run at or below the Absolute Maximum Voltages for your CPU, you should never experience degredation or lose of life on your CPU. Overclocking will not decrease the lifetime of your CPU if and only if certain criteria are met.

1.) Electrical Specification must be satisfied (1.55v for 65nm Core 2 Series and 1.45v for 45nm Core 2 Series, 45nm Core i7/i5 list 1.55v as their maximum, and 32nm Core i5 list as 1.40v. Make sure you check all other voltage specifications for VTT and CPU PLL. (Dram voltage on the i7 is a different story).

2.) Signal Quality must be clear (Overclock must be perfectly stable, GTL lanes may need to be tweaked)

3.) Mechanical specifications met (There is not a physical defect and the insides have not previously been gutted by running 1.9v through it)

4.) Thermal Specifications must be satisfied (The IHS temp must be below Tcase)

According to Intel, "Within functional operation limits, functionality and long-term reliability can be expected." This says nothing about running over stock voltages or stock clocks. Only that you need to be stable, cool, below the maximum voltage, and mechanically sound at any speed.

Interestingly enough, criteria 2 (Signal Quality) alludes to the idea that unstable overclocks cause CPU degredation. This actually makes sense if you think of unstable/inappropriate signals causing BSODs and other errors actually causing physical damage as the inappropriate signals move through the CPU at random.

For the exact wording in the Intel document

Quote:
Absolute Maximum and Minimum Ratings
Table 2-2 specifies absolute maximum and minimum ratings only and lie outside the
functional limits of the processor. Within functional operation limits, functionality and
long-term reliability can be expected.

At conditions outside functional operation condition limits, but within absolute
maximum and minimum ratings, neither functionality nor long-term reliability can be
expected. If a device is returned to conditions within functional operation limits after
having been subjected to conditions outside these limits, but within the absolute
maximum and minimum ratings, the device may be functional, but with its lifetime
degraded depending on exposure to conditions exceeding the functional operation
condition limits.

At conditions exceeding absolute maximum and minimum ratings, neither functionality
nor long-term reliability can be expected. Moreover, if a device is subjected to these
conditions for any length of time then, when returned to conditions within the
functional operating condition limits, it will either not function, or its reliability will be
severely degraded.

Although the processor contains protective circuitry to resist damage from static
electric discharge, precautions should always be taken to avoid high static voltages or
electric fields.

...
NOTES:
1. For functional operation, all processor electrical, signal quality, mechanical and thermal
specifications must be satisfied.
Source - Page 19

This may bring up the idea of OC Fade, but I have not seen example at or below 1.55v on a 65nm Core 2 Series that was completely stable (Prime95, LinX, Folding, ect.) or a 45nm Core 2 Series at or below 1.45v.

Quote from Intel to keep in mind

Quote:
Moreover, if a device is subjected to these conditions for any length of time then, when returned to conditions within the functional operating condition limits, it will either not function, or its reliability will be severely degraded.
Please use common sense, good cooling, and test stability stringently; and you shouldn't have any problems.

Cheers,
ChickenInferno
 
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7
#3 ·
thanks for the info
 
#7 ·
Quote:

Originally Posted by RemiX View Post
So if I were to set my TJ Max to 90(Q6600@3.6ghz) that would mean my idle temps are -1,-1,-5,-5 & load should be about in the 35'ish.

That is siick. xD

ps. the ambient becomes chilly in the morning

~RemiX
Remember though at the Other Side of TJ Max Section that at low temps at idle, using anything based on TJ Max is useless. Idle temps can be around plus or minus thirty. So if you are reading at -1 it could be as high as 29C or as low as -31C. My guess is you're probablly idling right above ambient. Load the cpu up on prime95 Small FTT to find a true temp. If still below 50C then great, but I have a feeling you might go a little higher than that.

Quote:

Originally Posted by Sullivan View Post
So setting my Tjmax to 90 on my q6600 g0 is good and safe, and my 20c temps are correct?
20C temps are correct in the standing that it is what the mobo/cpu are reporting as the core temp, but it is innaccurate because of the basic design of TJ Max. The sub-ambient temps are just normal readings due to the inaccuracies at temps far away from TJ Max. Load temps are basically the only ones that mean anything
 
#10 ·
Quote:

Originally Posted by RemiX View Post
Hello, ChickenInferno

Load temps within 5minute run is 44highest core.

~RemiX
Wow that's a nice temp. Just remember that it could be about a plus or minus 10 at that temp, but honestly I would love to be in that situation with temps that low. Maybe I will invest in a TRUE with a nice fan


Sullivan, Load up Prime95 Small FTTs to see what your load temps are. (I sense that C1E and speedstep are in effect and lowering your temps
 
#11 ·
We've talked about the TJMax settings that Intel has released and they have debunked their own values. I have now just gone by the Distance to TJMax (DTS) vs actually reading the temp.

For instance right now as I type this my computer is at 54c to TJMax, no matter what you change your TJMax to this number never changes.

EDIT: TJMax of 70 puts me at a 16c which is about 60F... My house is warmer then 60F :/ And my proc is at 3ghz with 1.4v.

I strongly suggest you put a disclaimer for yourself on this.

pink
 
#13 ·
Quote:

Originally Posted by Mr Pink57 View Post
We've talked about the TJMax settings that Intel has released and they have debunked their own values. I have now just gone by the Distance to TJMax (DTS) vs actually reading the temp.

For instance right now as I type this my computer is at 54c to TJMax, no matter what you change your TJMax to this number never changes.

EDIT: TJMax of 70 puts me at a 16c which is about 60F... My house is warmer then 60F :/ And my proc is at 3ghz with 1.4v.

pink
The actual values for when Core Temperature is approximately equal to TJ Max has never been "debunked." If you read the Other Side of TJ Max Section in my original post you will see that I clearly state how inaccurate idle readings are. So a 16C idle is very inaccurate exactly like I said it would be, and which you are claiming "debunks" my post. TJ Max does nothing for idle but give you inaccurate values and then it only gives accurate values for load when you are close to the TJ Max value.

Quote:

Originally Posted by crashnburn_819 View Post
Awesome info that I had to look up several times, now all in one convenient place! repped

I really only check my Distance to TjMax to be >20 to consider within reason. Is that gonna work or will I be throttling?
Since your thermal spec (tcase) is 61.4C and your TJ Max is 80C, then keeping a Dist to TJ Max of 20C would be more than enough to keep perfectly safe. You shouldn't really be throttling at all until you hit around 80C (Dist to TJ Max=0) or not at all if disabled in the bios.
 
#14 ·
Quote:

Originally Posted by ChickenInferno View Post
Since your max temp is 61.4C and your TJ Max is 70C, then keeping a Dist to TJ Max of 20C would be more than enough to keep perfectly safe. Technically, you could go up to a Distance of only 8.6, before doing damage, but I don't really reccomend that. You shouldn't really be throttling at all until you hit 61.4C.
That isn't how it works.

The thermal spec (tcase and tjmax are two different measuring points. You should reach thermal spec/tcase the same time you reach tjmax.

And spontaneous, or even overly rapid, damage won't occur at tjmax, that's jsut whent he chip will start to throttle (if thermal management features aren't disabled).
 
#15 ·
The thermal specification (this example E6300 L2) is 61.4C so at 61.4C according to Intel you can start doing damage. If you go beyond thermal specification all the way to TJ Max, then all this is doing is simply going beyond the accuracy point. Temps above TJ Max become more and more inaccurate because it's just not designed for those temps. TJ Max says nothing about damage only about the accuracy of the temps. Since Intel has said that thermal specification is 61.4C, then at any temp at or above 61.4C damage may or may not occur spontaneously or fast. No one can easily predict how heat damage will occur on a cpu unless you do something crazy like heating it to 100C with a max temp or 71C (Obviously it would be fried if left for any considerable amount of time)

I did however make a booboo by saying the throttling temp was 61.4. I didn't reread it.

Alot of information was learned after this post was written. Please refer to the first post for the correct information.
 
#16 ·
This has been debated several times, what I have found is this:

Testing my QX6850 at 3.6 GHz. with 1.352v using Orthos small FFT's will give these readings:

Ambient Room temp. = 21c.

Core Temp. using the 80c. TJ Max setting = 39c. Full load.

Core Temp. using the 100c TJ Max setting = 59c. Full load.

My conclusion is, 39c. full load is highly unlikely, 59c. full load seems more accurate to me.
 
#17 ·
E8400 CO @ 3.6ghz (TjMax 100c)
Calibration for RealTemp (TjMax was 95c when I did it)



Sensor Test w/ RealTemp (100c TjMax)



CoreTemp, RealTemp, and HWMonitor Temps



My only question in your thread is where do you get your calibration figures from, how, and did you need to adjust?

My example no calibrations needed, I have good sensors (but a lousey o'cr)
 
#18 ·
Quote:

Originally Posted by hogans View Post
This has been debated several times, what I have found is this:

Testing my QX6850 at 3.6 GHz. with 1.352v using Orthos small FFT's will give these readings:

Ambient Room temp. = 21c.

Core Temp. using the 80c. TJ Max setting = 39c. Full load.

Core Temp. using the 100c TJ Max setting = 59c. Full load.

My conclusion is, 39c. full load is highly unlikely, 59c. full load seems more accurate to me.
Okay, looking at the error chart as an example. Your first reported temp is 39C which since it is less than 50C, according to Intel you can only think of this as "a temp lower than 50." Most of my post is not about lowering your temps by changing the TJ Max to something that artifically makes it look like you are running cooler, but that until you are relatively near your TJ Max your values are just very inaccurate. Just looking at your distance to TJ Max value, at a distance of 41 any reading is going to be highly innaccurate regardless of what temperature it is reporting. This could be 39C plus or minus 20. By artifically calling the TJ Max 100C, you raise your reported Temp but the distance is still the same so the innaccuracy is still the same.

Quote:

Originally Posted by kpo6969 View Post
My only question in your thread is where do you get your calibration figures from, how, and did you need to adjust?

The values for TJ Max were found actually on OCN posted by your link to Tom's Hardware when you posted in this thread.

I only had to adjust Core Temp, because Real Temp and HWMonitor were already set to TJMax of 90C.
 
#20 ·
Quote:
My only question in your thread is where do you get your calibration figures from, how, and did you need to adjust?

My example no calibrations needed, I have good sensors (but a lousey o'cr)

Quote:
The values for TJ Max were found actually on OCN posted by your link to Tom's Hardware when you posted in this thread.

I only had to adjust Core Temp, because Real Temp and HWMonitor were already set to TJMax of 90C.
So you never actually calibrated your cpu, you just made all the TjMax the same.

Calibrating your cpu for RealTemp:

http://www.techpowerup.com/realtemp/docs.php

Calibration
The only way you are going to get some reasonably accurate reported temperatues is if you take the time to check and adjust your calibration. On the XtremeSystems forum, rge did some extensive testing with both an IR thermometer as well as mounting a calibrated thermocouple into the IHS lid over top of his processor. The calibration procedure involves running your CPU at a fixed MHz and at a reduced core voltage. This helps equalize the heat ouput of a wide range of CPUs so the difference in reported temperature between a Q6600 G0, an E8400 C0 and an E2160 with 1MB of cache should only be +/- 1C at these settings with the E8400 representing the mid point.

You need to set your CPU to default MHz for this test. The front side bus should be set to 266 MHz for 65 nm processors and to 333 MHz for the newer 45 nm processors. Core voltage needs to be set to 1.10 volts as reported by CPU-Z. The CPU multiplier needs to be set to 6.0 at idle or 12.0 for Core i7. You can either enter these values manually into your bios or you can also enable EIST, Enhanced Intel Speed Step, which is designed to drop your CPU close to these values automatically at idle. Not all motherboards properly support EIST so it's best to check using CPU-Z to confirm these values.

Open your computer case and compare your reported idle temperatures to your room temperature near your case or to your water temperature if you are water cooled. Based on the type of CPU cooling you are using, Core 2 based CPUs should be seeing reported temperatures similar to what rge saw during his testing.

COOLING...............................IDLE DEGREES ABOVE AMBIENT
High end water...............................6C above ambient
High end air (true push/pull) ........6-7C
High end air (1fan).........................7C
Mid air (zalman 9500)....................8-9C depending on fan rpm
Intel stock cooler...........................10-11C

If your reported temperature is too low then you will need to go into the RealTemp Settings window and use a positive calibration factor to increase your reported temperature. If your CPU is reading too high, you will need to use a negative calibration factor. On a multi-core processor during this test, you should have equal temperatures for all of your cores. Though this calibration test is done when your processor is idle, the calibration settings entered will improve the accuracy of your reported tempertures from idle to TJMax. Return your computer to your normal MHz and core voltage settings and if you need to, you can make some further minor adjustments to equalize your core temperatures at idle. You shouldn't need to make any major adjustments at this point.

Based on Intel's specs and during initial testing, the Core i7 CPUs seem to be more efficient and create less heat at idle compared to previous Core 2 Quad processors. Your results will likely be a couple of degrees less than the numbers listed in this chart depending on how your bios and Windows power management options are set.

Settings Window
Idle Calibration

Any value between -19.9 and 9.9 can be used to improve the accuracy of your reported temperatures. Refer to the Calibration paragraph above to determine what settings are appropriate for your processor. A unique value for each core can be set. The temperature sensors on each CPU are unique so for best results, RealTemp should be calibrated to your CPU.
 
#21 ·
Thank you kpo6969, I was getting ready to tell people about the awesome testing done by unclewebb and rge over at the REal temp thread on XS forums.

Here is the other thing everybody needs to keep in mind; The temperature at which your chip will throttle will vary from CPU to CPU, even with CPU's of the same exact model and VID. It can even vary from core to core. This is because, as the OP probably stated already, each chip is calibrated individually, thus making all the sensors and calibrations vary slightly from chip to chip. One Q6600 may have a TJMax of 95 another might be 97.
 
#22 ·
Quote:

Originally Posted by tbates1244 View Post
as the OP probably stated already, each chip is calibrated individually, thus making all the sensors and calibrations vary from chip to chip. One Q6600 may have a TJMax of 95 another might be 97.
The point of my post was to keep it very simply and easily understood. The point that you're alluding to is that what I have explained isn't an exact number but the numbers reported in post #1 are actually TJ Max Target values. These are the numbers that Intel was aiming for with each proccesor and most chips are close to the target.

The problem with calibrating to idle/stock temps/clocks is that you immediately introduce mass amounts of uncertainty into the readings. The article lists off possible values for temperature readings based on cooling type, but there are many reports of exceptionally "hot batches" of cpus, which would idle much higher than ambient temperature not due to the cooling but the thermal wattage dissipation. By saying that my cpu should idle around 8C higher at stock idle than ambient, I am already guessing at the capabilities of my cooler and at the heat it is dissipating. Depending on the cooler and the chip the uncertainty would just vary too much for my taste (Could be very accurate or could very inaccurate).

Intel documentation also alludes to the idea that distance to TJ Max is not reliable as it decreases. Thus, the documentation says that below 50C temperatures are saturated and considered inaccurate, but near TJ Max they are accurate. It is possible that you are setting an accurate temperature low, but that due to the non-linearity of the distance to TJ Max (non-linearity alluded to not specifically stated) you have actually set the load temperatures far from actual temps, but fairly accurate idle temps. This "calibration" may only be calibrating to lower temps and not higher temps. The only way to successfully test this would be to put a thermal diode on the cores themselves.
 
#24 ·
This should be stickied regardless of preference or belief...

Personally I'd love to test this further myself, but I'm terrified of carving out a thin channel in the IHS to insert a thermal probe. Instead I might just buy an IR thermometer and play with that first.

Quote:
The problem with this argument is that Intel has implied that the Distance to TJ Max values are not linear, and therefore you would have accurate idle temps (not important) and very inaccurate load temps (very important).
It would be interesting if there were a way to have TJmax work in a variable manner, where realtemp applies the newly calibrated TJmax when temps are around a specific threshold, yet when that threshold is broken the original TJmax is used...
 
#25 ·
Quote:

Originally Posted by MasterKromm View Post
It would be interesting if there were a way to have TJmax work in a variable manner, where realtemp applies the newly calibrated TJmax when temps are around a specific threshold, yet when that threshold is broken the original TJmax is used...
I'm sure that a program could be written with a very simple modification like a while wend loop. For example, if the calibration TJ Max was found to be 99C, then as long as the distance is far (value is innaccurate) the calibrated temp would be correct. When the distance becomes less than 40, the values become more accurate and therefore you could use the Intel numbers.

Quote:
While 1=1
.......While Dist TJ Max>40
...............99=TJ Max
.......Wend
.......90=TJ Max
Wend
I don't pretend to be that good at programming, but this seems like it would work.
 
#26 ·
Ive set the TJmax now in coretemp and HWmonitor and my temps look awesome.

I dunno weather to trust them though, i dont have a proper way of measuring my ambient tempreture but i just checked my central heating thermostat and it clicked 'on' at 18c so i assume that my ambient temp is around 18c. The stat is in another room so it could be colder or warmer in the computer room ( Feels colder IMO )

HWmonitor and coretemp report my idle temp at 18-19c

Are they right?
 
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