Sign in with
Sign up | Sign in

IDF Taipei: Intel Releases DTS Specs For All Core 2 Processors

By - Source: Tom's Hardware | B 6 comments

It has been a long time coming, but the pieces are slowly falling into place. Intel has now released the official Tjunction Max value for all 65nm and 45nm Core 2 processors at the Intel Developer Forum in Taipei.

In a previous report on the August IDF presentation in San Francisco, Tom’s Hardware discussed how the information provided by Intel had very little real-world value. The reason Tjunction Max (the temperature where thermal protection is engaged) is not the silver bullet for 45nm Core 2 processors is because the sensors suffer from extremely high amounts of "slope error," that is, they become less accurate as the real temperature moves further from Tjunction Max.

An Intel document (PDF) describes the error on Atom processors, which use the same or similar DTS as those on 45nm Core 2 processors :

"The digital thermal sensor (DTS) accuracy is in the order of -5°C +10°C around 90°C ; it deteriorates to ±10°C at 50°C. The DTS temperature reading saturates at some temperature below 50°C. Any DTS reading below 50°C should be considered to indicate only a temperature below 50°C and not a specific temperature. External thermal sensor with “BJT” model is required to read thermal diode temperature."

According to Intel, if the actual temperature is below 50°C the temperature can’t be trusted at all. With calibration, the slope error can be offset to an extent, but the reported temperatures will never be as accurate as those which are reported by the DTS on 65nm processors. Furthermore, the sensors can sometimes "stick," particularly at lower temperatures, and the worst of these sensors can’t be calibrated properly.

Unlike their 45nm counterparts, the DTS for 65nm is much less affected by slope error, so that even a temperature readout that has not been calibrated can give a reasonably close representation of the actual temperature. The only major factor which will affect readings is Tjunction Max. Since the 65nm CPUs were released, enthusiasts and developers of temperature monitoring software have debated over the Tjunction Max. It was hoped that Intel would disclose these details at the August IDF ; however, we were to be disappointed. A few months later and Intel has finally decided to disclose the Tjunction Max for every processor in the Core 2 line, both 45nm and 65nm, as well as Xeon server CPUs. The Tjunction Max values for all Core 2 processors are as follows :

65nm Desktop CPUs
ModelTj Max (B2/B3/L2)Tj Max (G0/M0)
E6000 and E4000 series70°C80°C
X680075°C85°C
Q6000 series80°C90°C
QX6000 series80°C90°C
QX68xx series80°C80°C
E1000 series75°C85°C

45nm Desktop CPUs
ModelTj Max (Stepping unspecified)
E8000 and E7000 series100°C
Q9000 and Q8000 series100°C
QX965095°C
QX977x85°C

65nm Xeon Dual-Core CPUs
ModelTj Max (Stepping unspecified)
E7220, E721080°C
7100 series100°C

65nm Xeon Dual-Core CPUs
ModelTj Max (B2)Tj Max (G0)
5080, 506080°C90°C
5063, 5050, 503080°C90°C
5160N/A80°C
5150, 5140, 5130, 5120, 5110N/A80°C
5148N/A80°C
L5138N/A100°C
3000 series80°C90°C

65nm Xeon Quad-Core CPUs
ModelTj Max (Stepping unspecified)
X735090°C
E7340, E7330, E7320, E731080°C
L734580°C
X5000 series90/95°C
E5000 series80°C
L5000 series70°C
L531895°C
X3230, X3220, X321090°C
XE90°C
XEE80°C

45nm Xeon Single-Core CPUs
ModelTj Max (Stepping unspecified)
L310495°C

45nm Xeon Dual-Core CPUs
ModelTj Max (Stepping unspecified)
X52xx series90°C
E524090°C
E5220, E520570/90°C
L524070°C
L5238, L521595°C
E3120, E3113, E311095°C
L311095°C

45nm Xeon Quad-Core CPUs
ModelTj Max (Stepping unspecified)
E7440, E7430, E742090°C
L744580°C
X54xx series85°C
E54xx series85°C
L540895°C
L5430, L5420, L541070°C
X33xx95°C
L336090°C
X33xx series95°C
L336090°C

45nm Xeon Six-Core CPUs
ModelTj Max (Stepping unspecified)
X746085°C
E745585°C
L745585°C

The above data will mean that for some users the temperatures currently being reported for their cores are actually quite a fair amount off ; assuming we take Intel’s word for these maximum temperature values. For example, most temperature reporting programs would use 85°C as the Tjunction Max for a B2 E6600. According to Intel, the "official" Tjunction Max for this processor is only 70°C. That means that for a program which does not take into account any slope error, the temperature would be reported 15°C too high.

Of further interest is that many enthusiasts have done extensive testing to approximate Tjunction Max where it had not been specified. For the 45nm processors, Intel’s data generally aligns with the results of community testing. However, for 65nm the values provided by Intel are significantly different for some processors than what testing has shown. It may very well be that Intel has caused even more confusion than before.

You can expect most software developers to update their programs in the near future to reflect the information provided by Intel.

Display 6 Comments.
This thread is closed for comments
  • 2 Hide
    spuddyt , 22 October 2008 05:02
    so the 45nm's can go up to 100 degrees?!
  • 2 Hide
    Anonymous , 22 October 2008 16:09
    Yes, but dont count on any current cpu temprature programs showing what your real tempratue is, till they updated with this new data.
  • 1 Hide
    wild9 , 22 October 2008 21:57
    If the manufacturing process is tried and trusted (as in, how many Core 2 Duo's have ever over-heated under nominal voltages), does it really matter if the sensor is a bit off? I can understand the reservations in mission-critical scenario's, but the attraction of using cooler, 45nm should negate these fears. They already run cool even at 65nm.
  • 1 Hide
    Anonymous , 18 November 2008 21:58
    How can this be?

    I have a Q6600 G0 running on at 3ghz (333*9) and with a TJMax 100 (CoreTemp Default) it idles at 24~28*C with an Arctic Freezer Pro. Which sounds about right.

    Ambient Temperature is around 15*C.

    If I set my TJMax to 90, it reckons my chip idles at 14~18*C...

    Sub-ambient with an air cooler....That is impressive :p  (and not possible!)
  • -1 Hide
    carmaster22 , 8 December 2008 08:20
    I agree with the post directly above. I have an E4500 in my Dell work PC (100% bone stock) and CoreTemp reports the idle temps at 20C with a Tj Max of 85 while the ambient room temp is around 20C. That's believable since it's a plain old Dell PC and doesn't do much. But figure in Intel's "correct" Tj Max and my CPU is idling at 5C. That's totally impossible.
  • -1 Hide
    mr roboto , 3 January 2009 10:18
    Perhaps, just perhaps Intel is giving out incorrect data so older 65nm CPU owners will shorten the lifespan or even burn out their CPU's and upgrade to i7? Wilder conspiracies have been proven true.

    I'm partially joking here but if Intel doesn't clear this up it looks a bit sketchy.