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Which Temperature Reading is 'more' accurate?

Last response: in Overclocking
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March 1, 2007 1:47:32 PM

i've been going through the 'Core 2 Duo Temperature Guide' and testing my system with the temperature monitoring softwares, i don't get really the 'Tjunction (TAT and Core Temp) is Tcase + 15c = Tjunction'

idle = 41°C (Asus' PC ProbeII/speedfan) and 37/39°C (tat/core temp)
load = 57°C (Asus' PC ProbeII/speedfan) and 55/57°C (tat/core temp)

well i guess my question is, which one is more accurate?
so which 'rule' should i follow:

'(E) Tcase Load should not exceed ~ 55c.
(F) Tjunction Load should not exceed ~ 70c.'


System: all stock speeds/fans
cpu: e6600
mobo: asus p5b-e
ram: ocz pc6400
gfx: x1950xt
psu: cheap 450W
HD: 2x seagate 250gb in raid 0
Case: icute 0508 (lol, it has 12cm, 14cm, 25cm fan)
(http://www.overclockersclub.com/reviews/icute_case.php)
March 1, 2007 2:35:55 PM

TAT and Core Temp are the more accurate temp reading programs. Both read the temp from the actual core not a temp probe based somewhere either on the MB or CPU and gives a reading. Just use Core Temp or TAT and you are set man I mostly use Core Temp for just watching temps a small program and i use TAT to maybe stress my CPU out a little bit and monitor its temps with logging. Both have logging mind you i just only log with TAT.

EDIT: Hmm what is weird to me is that TAT and Core Temp are reading different Temps for you. Such as right now i have both programs open and they are reading the EXACT same temps for both cores. Even under load they both read the same temps for each core. When you check these temps are do you have both programs open or are you reading the temp in one then closing and opening the other?
a b à CPUs
a b K Overclocking
March 1, 2007 4:19:40 PM

patchez, the following is my response from Which Temperature Reading is 'more' accurate?:

Quote:
...i don't get really the 'Tjunction (TAT and Core Temp) is Tcase + 15c = Tjunction'

idle = 41°C (Asus' PC ProbeII/speedfan) and 39°C (tat/core temp)
load = 57°C (Asus' PC ProbeII/speedfan) and 57°C (tat/core temp)

which one is more accurate?
so which 'rule' should i follow:

(E) Tcase Load should not exceed ~ 55c.
(F) Tjunction Load should not exceed ~ 70c.'

System: stock speeds/fans
cpu: e6600
mobo: asus p5b-e
Case: icute 0508 (12cm, 14cm, 25cm fan)


Variables

Ambient = ?????
Chipset = 965
C2D = E600
CPU Cooler = Stock
Frequency = 2.4 Ghz
Load = TAT 100%
Motherboard = Asus P5B-E
Vcore = Stock

patchez, you were very close to working out the answer for yourself. Your Tcase value is obviously too high for stock clock & Vcore. For your situation, the following items define the problem:

Parameters

(B) Tcase Idle should be ~ 2 to 15c higher than Ambient.

(D) Tjunction should be ~ 15c higher than Tcase.

The answer is that Tcase is offset by +15c due to incorrect firmware CPU thermal tables in BIOS. This type of offset is a common problem:

Variables

Quote:
The typical ~ 15c difference between the single Tcase temp, and the dual Tjunction temps can be erroneous due to calibration inaccuracies in chipsets, BIOS releases, driver versions, and motherboard utilities. Intel’s spec for thermal sensor accuracy is +/-1c, so temperatures can be quite accurate on hardware / firmware platforms free of manufacturer's deficiencies. Even false temperatures have offsets which can be analyzed, and when given correction factors, may still be reasonably accurate.


Corrected Temperatures:

idle = 26°C (Asus' PC ProbeII/speedfan) and 39°C (tat/core temp)
load = 41°C (Asus' PC ProbeII/speedfan) and 57°C (tat/core temp)

As you can see, your corrected temps now fit the Parameters, and Tcase + ~15c = Tjunction.

Hope this helps, and enjoy your rig! :D 

Comp 8)

Core 2 Duo Temperature Guide
Related resources
a b à CPUs
a b K Overclocking
March 1, 2007 4:40:21 PM

Fate0N3, regarding accuracy:

Quote:
Specifications

...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.

All Desktop C2D's = 85c
Ambient Temperature = 22c
Idle to Load Delta Max = 25c
Tcase + 15c = Tjunction
Thermal Sensor Accuracy = +/-1c

Variables

The typical ~ 15c difference between the single Tcase temp, and the dual Tjunction temps can be erroneous due to calibration inaccuracies in chipsets, BIOS releases, driver versions, and motherboard utilities. Intel’s spec for thermal sensor accuracy is +/-1c, so temperatures can be quite accurate on hardware / firmware platforms free of manufacturer's deficiencies. Even false temperatures have offsets which can be analyzed, and when given correction factors, may still be reasonably accurate.


Core Temp typically reads ~2c higher than TAT:

Quote:
Interpretation

** The second part of the spec refers to mobile processors without an integrated heat spreader, measured by internal Digital Thermal Sensors. Since Intel's Thermal Analysis Tool (TAT) is a Notebook tool, and desktop C2D's have an integrated heat spreader, the software tool "Core Temp" compensates ~ 2c higher, and shows Intel's Thermal Junction Maximum spec (Tj max) of 85c as the shutdown limit. 80c is overtemp, where TAT redlines and the CPU throttles, 75c is hot, 70c is warm, and 65c is safe. The dual Thermal Junction sensors are how Tjunction temps are measured. Tjunction is the dual core temp displayed by TAT and by Core Temp.


Hope this helps.

Comp 8)

Core 2 Duo Temperature Guide
March 1, 2007 9:36:59 PM

lol, hey Fate0N3... Tat and CoreTemp read the same for me actually... the two numbers are actually the temps for each processor.

And thanx again CompuTronix!

FYI: alt 0176 = °
March 2, 2007 2:40:29 AM

Ahh that is cool after reading it again i thought you could be talking about the temp for each core of the CPU. But i wasn't for sure man srry.
!