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Minimum temp for Core 2 Duo?

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  • CPUs
  • Cooler Master
Last response: in CPUs
October 10, 2009 4:33:01 PM

Hi all,

I have problems reducing the temperatures of my C2D E7500 and I hope you experts can assist.

My current setup is:
C2D E7500
Asus P5B-E Plus
MSI N9600GT
Kingston 5300 667 2gb RAM
3 x 12cm fans + 2 x 9cm fans
Cooler Master 430W PSU
Temp Software: Real Temp, SpeedFan

I was previously using E4300 with Cooler Master Hyper TX and idle temps are 34 degrees with slight OC to 2.2ghz. With load (playing games such as Call of Duty and Company of Heroes) it goes up to 45 degrees.

Recently I changed to E7500, flashed my BIOS to version 0638, and used a cheap Cooler Master thermal compound to attach the Hyper TX to the new CPU. Temps were at 41 and 40 (idle) and up to 49-51 (load) for 1 core. The other Core remains unused at 40 degrees.

To lower temps, I changed the thermal paste to Artic Cooling MX-2 but got the same idle temps of 41, though load temps maxed out at 48.

To further lower temps, I bought a Noctua NH-C12P but the idle temps remained at 41, though load temps maxed out at 46. There is something wrong as the cooling properties of the Noctua and MX-2 should have brought about a change from the initial set-up i.e. idle temp for Cores should drop below 41 and 40 degrees.

I tried overclocking to 3.6ghz and load temps maxed out at 53 degrees. Now I'm not so much concerned about how high the temps are but rather, why the base temp of 41 and 40 remains unchanged. Could it have something to do with my P5B-E plus motherboard not being P45 chipset? Or could it be that the E7500 has a minimum temp of 41 and 40 and it can't go lower than that?

I don't want to upgrade my CPU chassis if additional airflow is not going to solve the problem. I suspect it could be something to do with the temp diodes or motherboard.

Appreciate any comments. Many thanks for reading!

More about : minimum temp core duo

a c 308 à CPUs
October 10, 2009 5:23:05 PM

Quiescence-X ,

There's nothing unusual here. Many 45 nanometer Core 2 processors have poor quality Digital Thermal Sensors (DTS) that "stick" and won't read below a certain temperature. Intel has stated that since the DTS is desinged for overtemp protection, the values may be reasonably accurate at high temperatures, but may become unresponsive below 50c, and are unreliable at low temperatures, such as idle, due to factory calibration deviations, slope error and non-linearity. Use Real Temp's "Sensor Test" to see your DTS movements.

Regardless, your primary concern should be load. Temperatures and overclocking are all about specifications, so it's very important to be specific. If we're not, then the topic makes about as much sense as comparing apples-to-oranges thermal fruit salad in a blender! :pt1cable:  My objective is to assure that enthusiasts understand Intel's specifications, standards and test methods, so they can better decide how to apply and manage their overclocking options.

From Intel's Processor Spec Finder - http://processorfinder.intel.com/List.aspx?ParentRadio=...

E7500 variants:

Vcore Max 1.3625
Tcase Max (CPU temperature) 74c
Tjunction (Core temperature) 79c

From the Core i7 and Core 2 Temperature Guide - http://www.tomshardware.com/forum/221745-29-sticky-core...


"Section 1: Introduction

Core i and Core 2 processors have 2 different types of temperature sensors; a CPU case (not computer case) Thermal Diode centered under the Cores, and Digital Thermal Sensors located on each Core. The case Thermal Diode measures Tcase (Temperature case), which is CPU temperature, and the Digital Thermal Sensors measure Tjunction (Temperature junction), which is Core temperature. Since these sensors measure 2 distinct thermal levels, there is a 5c temperature difference between them, which is Tcase to Tjunction Gradient. Core i7’s / i5’s and Core 2 Quad’s have 1 Tcase and 4 Tjunction sensors, while Core 2 Duo's have 1 Tcase and 2 Tjunction sensors ...

... The monitoring utilities provided by motherboard manufacturers monitor CPU temperature, while some popular freeware utilities monitor Core temperatures ... Real Temp ... is recommended for users interested in monitoring Core temperatures only ... SpeedFan monitors Tcase (CPU temperature) and Tjunction (Core temperature) ... "


The Thermal Specification shown in Intel's Processor Spec Finder is Tcase Max (CPU) not Tjunction (Core), which is a very common misconception among most enthusiasts. Since there's a 5c gradient between the CPU sensor and the Core sensors, (shown in the following Intel document) - http://arxiv.org/ftp/arxiv/papers/0709/0709.1861.pdf - just add 5c to the value shown in the Spec Finder to determine the corresponding Core temperature, which is 79c for the E7500.

Intel's second and frequently misunderstood Thermal Specification, Tjunction Max, (100c for the E7500) applies to overtemp protection such as Throttle and Shutdown, so you don't toast your transistors. As such, any E7500 Core temperatures which exceed 79c should be considered "overtemp". Further, when specifications are exceeded, then processor degradation becomes a concern, which is explained in the following AnandTech article - http://anandtech.com/cpuchipsets/intel/showdoc.aspx?i=3...

Prime95 Small FFT's is the Standard for processor thermal testing, because it's a steady-state 100% workload which yields steady-state temperatures, whereas Blend is a memory cyclic workload which yields fluctuating processor temperatures. Small FFT's will reach 97% thermal saturation within 7 to 8 minutes, so a 10 minute test is adequate. Thermal testing should be conducted as close as possible to 22c (72f) Standard ambient, with case covers removed, the computer clear of any desk enclosures, and all fans at 100% RPM to eliminate cooling variables, and to produce consistent and repeatable results for comparisons. If the Gradient between CPU temperature and "mean" (average) Core temperature is not ~ 5c, then BIOS is incorrectly coded. CPU temperature and Core temperatures can be individually calibrated in SpeedFan by following the Calibrations Section in the Temperature Guide.

OCCT and Burn Test (reminiscent of TAT) use LinPack, which shows thermal signatures that resemble the ups and downs of a bad day on the stock market, and cycle between light workloads, through test segments which spray all processor registers with all one's, (100% thermal load, which equates to 115% workload), and can push an overclocked E7500 at Vcore Max 1.3625, right on past Tcase Max! :o 

Since there are very few applications or games that will spike, let alone sustain processor workloads beyond 70% to 85%, utilities which load all registers with all one's are not representative of real-world computing. While these utilities are certainly very useful for stability testing, they are inappropriate for thermal testing. The 3DMark benches are excellent for stability testing, as are applications for ripping and encoding.

To make sense of CPU temperature and Core temperature, just compare them to a 4 cylinder car that has 5 temperature guages; 4 of the 5 guages are cyclinder head temperatures (closest to the heat source), and the 5th guage is the overall engine temperature, which is 5c lower than the other 4 guages, and is the temperature guage with which we're all familiar. We know the "red" or HOT zone for the E7500 is 74c (Tcase Max) on the engine temp guage and 79c (Tjunction) on the cylinder head temp guages, but if we push the engine too hard and peg all the guages, (95c Tcase overtemp / 100c Tjunction Max) then the engine will shut down.

If you'd like to learn more about processor temperatures, then just click on the link in my signature.

Hope this helps,

Comp :sol: 
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October 11, 2009 3:39:10 PM

Hello CompuTronix,

Thank you so much for sharing your knowledge. Its comforting to know that the minimum temps are not meant to be accurate at low temps, but at the same time I feel silly for investing so much in a new Noctua heatsink when my CM Hyper TX is perfectly good for my everyday use i.e. playing CPU-intensive games.

The realtemp sensor tests shows a movement of 3 for Core 0 and 0 for Core 1. Is this of significance?
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a c 308 à CPUs
October 11, 2009 4:16:43 PM

Absolutely! It proves that your processor ischt gerschtunkken sensors. :heink:  If they respond properly at 100% workload during Prime95 Small FFT's, then count your lucky stars, and just ignore Core temperatures at idle. :D  You can instead rely on CPU temperature for idle, (as well as load), but you'll need to calibrate it in SpeedFan, since Real Temp shows Core Temperatures only.
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October 12, 2009 4:56:29 AM

I'm sorry but can I assume that my 'gerschtunkken' are screwed up? (not too sure what the word means - sounds bad though) Is this a manufacturing defect?

Right now my CPU temp using speedfan idles at around 36-38 degrees. Does that mean that my Core temps are + 5 degrees i.e. they are idle at 41-43 degrees?

The idle temps seem rather high when compared to the temps which the Noctua cooler can seemingly obtain when reviewed by websites such as Frostytech, tweaktown, overclockers club etc. Of course the methodology is different and hence resulting in different temps readings. Can you advise which is a good website I can go to for objective and valid reviews of the heatsink coolers?

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a b à CPUs
October 12, 2009 5:05:12 AM

He's joking. It's not even a real word.

Nothing 'wrong' with those idle temps.
Also want to mention that the temp sensors are designed for overtemp protection, and aren't accurate below 44C or so, mine always sit at 42C.

It's the under-load temps that matter.
Run Prime95 on Small FFT mode, see how high it goes, stop it if it goes over 70C but I doubt it will.
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a c 308 à CPUs
October 12, 2009 3:49:23 PM

SpidersWeb said:
Also want to mention that the temp sensors are designed for overtemp protection, and aren't accurate below 44C or so, mine always sit at 42C.
SpidersWeb,

From my 1st post:

... Many 45 nanometer Core 2 processors have poor quality Digital Thermal Sensors (DTS) that "stick" and won't read below a certain temperature. Intel has stated that since the DTS is desinged for overtemp protection, the values may be reasonably accurate at high temperatures, but may become unresponsive below 50c, and are unreliable at low temperatures, such as idle, due to factory calibration deviations, slope error and non-linearity. Use Real Temp's "Sensor Test" to see your DTS movements... said:
... Many 45 nanometer Core 2 processors have poor quality Digital Thermal Sensors (DTS) that "stick" and won't read below a certain temperature. Intel has stated that since the DTS is desinged for overtemp protection, the values may be reasonably accurate at high temperatures, but may become unresponsive below 50c, and are unreliable at low temperatures, such as idle, due to factory calibration deviations, slope error and non-linearity. Use Real Temp's "Sensor Test" to see your DTS movements...
Quiescence-x said:
Right now my CPU temp using speedfan idles at around 36-38 degrees. Does that mean that my Core temps are + 5 degrees i.e. they are idle at 41-43 degrees?
Quiescence-X,

If you read my Temperature Guide, you can calibrate your temperatures in SpeedFan. It won't correct your "sticking" Core temperatures at idle, but it'll give you accurate Core temperatures at load, and accurate CPU temperatures at idle and load. It's not rocket science; it's just following directions and a little 4th grade math, so anyone should be able to do it.

Comp :sol: 
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