TCase higher than TJunction. Why? (CompuTronix?)

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bh626pro

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May 18, 2007
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Here is a screen of my new PC. It clearly shows, through various tools, that the CPU Tcase temp is higher than the 2 core temps by 13C. How does this make sense? Did I connect something on the MB wrong? What should I trust?

At Idle;

Core 0,1 are 29C (Speedfan, TAT, CoreTemp)
CPU is 41C (Asus Probe, Speedfan)

Brendan
--------------------------------------
e6600 @3000 mhz/stock heatsink
Asus P5B-e/latest bios 1202
Corsair XMS2 6400c4/2gb
74 Gb raptor
320 Gb Seagate
Radeon X1950 Pro
Screen.jpg
 
You have the temps backwards. The individual core readings are Tcase and the single CPU temp is tjunction.

That is how it is supposed to look.

Findings

(A) TAT can be used simultaneously with SpeedFan for benchmarking Desktop C2D's at 100% Load.

(B) The Delta between Tcase (BIOS, Motherboard Utilities and SpeedFan: CPU or Temp X) and Tjunction (TAT and SpeedFan: Core 0 / Core 1) is ~ 15c +/- 3c.

(C) 50c Tcase and 65c Tjunction are safe and sustainable temperatures.
Click to expand...

In your screen shot core 0 = tcase and CPU = tjunction [speedfan]
 
I don't think so. Reading through Computronix' post says that the core temps are ~15C hotter than the die temp (makes sense). Core is what TAT measures.

Again, Speedfan shows a die temp of 41C
TAT, coretemp etc show core of 29C

This doesn't make sense.

Any ideas?
 
Some users also may not know that C2D's feature 3 sensors at 2 different temperatures; a single on-die Tcase sensor (between the Cores), and dual Tjunction sensors (one within each Core).
Click to expand...

Ok there seems some inherent contradictions in the temp guide, things that did not exist when I originaly read it.

So tcase = 41c and tjunction = 29c according to CompuTronix and based on the following, right?

Tips

(A) Tcase = SpeedFan: CPU or Temp X.

(B) SpeedFan: Temp 1, 2 or 3 = Temp X.

(C) Tjunction = SpeedFan: Core 0 / Core 1.
Click to expand...

However, I have never seen a screenshot of SpeedFan with Core 0/1 > CPU which is weird. My system with Speedfan is the same as yours, Core 0/1 < CPU.

Parameters

(B) Tjunction is always ~ 15c higher than Tcase. [note this one]

(C) Tcase is always higher than Ambient.

(D) Tcase Idle should be ~ 1 to 15c higher than Ambient.

(E) Tjunction Idle should be ~ 15 to 30c higher than Ambient.
Click to expand...

Based on your screenshot your temps are fine.
 
bh626pro, I can't help you without complete information. From the Guide:

Background

...when expressing Idle & Load test Results, it's also necessary to define the Variables as:

Results

Tcase = Idle & Load
Tjunction = Idle & Load, Hottest Core

Variables

Ambient = Intake Temp
Chipset = Model
C2D = Model
CPU Cooler = Model
Frequency = CPU Clock
Load = Test Program
Motherboard = Model
Vcore = CPU Voltage
Click to expand...

Testing

Vcore = Manual
C1E / EIST = Disabled
CPU Fan = Manual, 100%
Computer Case Fans = Manual 100%
Computer Case Covers = Installed
Primary Test = TAT @ 100% 10 Minutes
Alternate Test = Orthos @ P9 Small FFT’s 10 Minutes
Click to expand...

Results

Tcase (Motherboard Utilities) = 30c Idle, 50c Load (SpeedFan: CPU or Temp X)
Tjunction (TAT) Hottest Core = 45c Idle, 65c Load (SpeedFan: Core 0 / Core 1)


Variables

Ambient = 22c
Chipset = 975X
C2D = E6600
CPU Cooler= AC Freezer 7 Pro
Frequency = 3.5 Ghz
Load = TAT @ 100% 10 minutes
Motherboard = Asus P5W DH
Vcore = 1.4
Click to expand...

Hope this helps,

Comp 8)
 
SuperFly03, there are no contradictions in the Guide, but there are many examples on this Forum of SpeedFan screenshots which correctly show Tjunction values (Core 0 / Core 1) higher than Tcase (CPU or Temp X). Your advice to bh626pro is unsound:

Based on your screenshot your temps are fine.
Click to expand...

Respectfully, please re-read the Guide with emphasis on comprehension. There's alot of information to take in, so only a few users "get it" the first time. Many need to read it several times, and unfortunately, there are some who will never "get it".

The Guide is not a document which I take lightly. Every concept, every paragraph, every sentence, every word, and every punctuation has been painstakingly thought out. I can't begin to estimate how many hundreds of hours of research and effort went into it, as well as the updates and edits, and how many thousands of users it's helped. If the Guide were invalid or contadictory, it would never have become a THG Forum "Sticky".

Hope this helps,

Comp 8)
 
Computronix, here are the info fields you requested, below in red. I still don't get it - why is TCase > Core?

My concern is that my Mobo is defective somehow. Is there a BIOS setting that would affect the temperature readings?

Setup

Asus P5B-E
1202 BIOS
Vcore = Manual
C1E / EIST = Disabled
CPU Fan = Manual, 100%
Computer Case Fans = Manual 100%
Computer Case Covers = Installed
Primary Test = TAT @ 100% 10 Minutes

Brendan's Results

Tcase (SpeedFan CPU and Asus Probe CPU) = 41c Idle, 56c Load
Tjunction (TAT and SpeedFan: Core0/Core1) Hottest Core = 30c Idle, 44c Load

My BIOS reads around 42C for the "CPU Temperature", so it would seem that the Tcase (SpeedFan CPU and Asus Probe CPU temps) are correct. So the question remains; is there any logical reason that the TJunction core temps are lower than the TCase? {EDIT} Yes! if PECI is disabled - see below.

Variables

Ambient = 22c
Chipset = 965P
C2D = E6600
CPU Cooler= Stock Intel
Frequency = 3.0 Ghz
Load = TAT @ 100% 10 minutes
Motherboard = Asus P5B-E
Vcore = 1.42

bh626pro, I can't help you without complete information. From the Guide:
Click to expand...
 
The temp readings depend on how the BIOS is setup in the Asus P5B mobo. I read through most of this 141 page thermal design doc from Intel found at http://www.intel.com/design/processor/designex/313685.htm.

Interesting points from the doc;

Digital Thermal Sensor
The Intel Core™2 Duo desktop processor E6000/E4000 sequence introduces the Digital Thermal Sensor (DTS) as the on-die sensor to use for fan speed control (FSC). The DTS can be accessed by two methods. The first is via a MSR (model specific register). The value read via the MSR is an unsigned number of degrees C away from TCC activation (Tjunction in CoreTemp). The second method which is expected to be the primary method for FSC is via the PECI interface. The value of the DTS when read via the PECI interface is always negative and again is degrees C away from TCC activation (Delta to TJunction).

PECI - Platform Environmental Control Interface
The PECI interface is a proprietary single wire bus between the processor and the chipset or other health monitoring device. At this time the digital thermal sensor is the only data being transmitted. Core 2 Duo processor E6000 and E4000 sequences do not have an on-die thermal diode.

Design Specs
Intel states that damage to the processor is likely if the temperature exceeds 68C or 155F, which can be avoided by using Thermal Management. In fact the doc states "To maintain compatibility with previous generations of processors, which have no integrated thermal logic, the Thermal Control Circuit portion of Thermal Monitor is disabled by default. During the boot process, the BIOS must enable the Thermal Control Circuit. Thermal Monitor must be enabled to ensure proper processor operation. "

What To Do?
In the BIOS;
> enable TM Management
> enable PECI - this seems to put the temps right. TCase is now lower than Core.

My Results at Idle
PECI disabled - [BIOS; CPU 33C, MB 41C]. CoreTemp 32C. CPU* 45C
PECI enabled - [BIOS; CPU 45C, MB 41C]. CoreTemp 32C. CPU* 24C

* The CPU read 24C in Asus Probe, SpeedFan, and AI Suite. Ambient temp was 18-20C

At load with PECI on, Core was 59C, CPU was 49C
 
This is an answer I can possibly get behind... need to reflect on it for a moment and let it sink in.

Good work. 8)

There is something I am missing in the actual numbers... I am trying to figure out how the difference between an unsigned number and a negative number function in the calculation of the temperature. I understand the difference but the end result is giving me issues. I would like to know how the system goes from 45c Tc to 24 Tc...... :idea:

Wait I think I have it... nope, damn it.

I got nothing without a forumla... :?

This still puzzles me.

Side note: WTF is your bios reading as a temp now? lol. 45c appears nowhere.
 
I'm glad you got it figured out. Unfortunately my mother board doesn't have either of those options. I have an Intel D975BXB2. I'm gonna start a new thread and hopefully Compu Tronix can help me get squared away.
 
I had this problem before too, all you to do is download speedfan and put an offset of +15*C on the Tjunctions.
Click to expand...

But that wouldn't change the temps that are reported from TAT. And from what I understand, those are the actual temps which are taken from diodes inside the cores...
 
I had this problem before too, all you to do is download speedfan and put an offset of +15*C on the Tjunctions.
Click to expand...

With what justification for that arbitrary offset? Just so they conform... there has to be a reason, not just "because."
 
With what justification for that arbitrary offset? Just so they conform... there has to be a reason, not just "because."
Click to expand...

This justification, the holy C2D temperature Guide:

Troubleshooting

(C) SpeedFan 4.32 can be configured to correct for Tcase and Tjunction Offsets.


Offsets

If temperatures don’t meet the Parameters, then SpeedFan 4.32 can configure Offsets to correct for Tcase (CPU or Temp X) and Tjunction (Core 0 / Core 1). From the “Readings” tab, click on the “Configure” button, then click on the “Advanced” tab. Next, click on the “Chip” field directly under the tabs, then use SpeedFan’s “Help and HOW-TO” icon included in the installation Program Group.

Under “Contents” click on “How to configure” then click on “How to set Advanced Options”. Read this section including “Other interesting options” and “Temperature x offset". When configured, SpeedFan will display all 3 Tcase and Tjunction temperatures correctly. SpeedFan is also extremely useful for observing temperatures and Vcore using the “Charts” tab, while thermal benchmarking with TAT.
Click to expand...

Parameters

(A) Vcore should not exceed ~ 1.5v.

(B) Tjunction is always ~ 15c higher than Tcase.

(C) Tcase is always higher than Ambient.

(D) Tcase Idle should be ~ 1 to 15c higher than Ambient.

(E) Tjunction Idle should be ~ 15 to 30c higher than Ambient.

(F) Tcase Load should not exceed ~ 60c with TAT, and 55c with Orthos.

(G) Tjunction Load should not exceed ~ 75c with TAT, and 70c with Orthos.

(H) Idle to Load Delta should not exceed ~ 25c.

(I) Tjunction Results are Hottest Core Idle and Load.
Click to expand...
 
I have read that, but just because tjunction should be 15c higher than tcase doesn't mean the whole 15c goes as an adjustment to tjunction. Your tcase could be reading too low. This is why Comp needs so much information abuot ambient, configuration, cooling, settings, etc. before he recommends offsets.
 
it doesnt say "Tjunction should be ~15c higher then Tcase" it says "Tjunction is ALWAYS ~15c higher then Tcase". So I dont see what all the fuss is about. The actual offset probly lies somewhere inbetween 12-18c so I dont see why 15c offset is the end of the world.
 
Wouldn't TAT's TJunction be the baseline? those temps can't be changed. I'm not looking to argue. I'm just trying to wrap my head around this.
 
T-junction although it is a term used in the mobile platform is actually the point at where TCC activation occurs (somewhere around 85C).
The core temps are read through the PECI and are in negative numbers away from TCC activation
85C minus 56 or -56C = 29C(core temp)
This reading of 29C is most likely in error from either the bios revision out of date or PECI has been disabled in bios.
Some motherboard manufactures are slower to update the bios than others and that’s why we see a few temps out of line.
 
How do you enable PECI on an evga 680i mobo though? I didn't see anything in the BIOS that resembled it. I am on p27 BIOS which I think is from march or something like that.
 
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