E8500 Max Temp

MasterG · Sep 11, 2008

First of all, take a look at page 79 table 28.

http://download.intel.com/design/processor/datashts/318732.pdf

It shows data on the maximum core temperature for the E8000 series. As far as I can tell, the max temperature should be 72C. Real Temp says it is 95C though which is awfully hot. I'd believe the Intel spec sheet before I'd believe Real Temp, but I'm confused why they list a variety of power levels with separate max temps. The TDP for the E8500 is 65W so is that what determines the max core temp? I'm running overclocked right now so I'm probably running above TDP right now. Would the max core temp then change?

Perhaps someone with some more experience could explain.

deeppow · Sep 11, 2008

MasterG said:
...

It shows data on the maximum core temperature for the E8000 series. As far as I can tell, the max temperature should be 72C. Real Temp says it is 95C though which is awfully hot.

Most likely the temp sensors is stuck on the core. Run the sensor test RealTemp has.

MasterG said:
...
I'd believe the Intel spec sheet before I'd believe Real Temp, but I'm confused why they list a variety of power levels with separate max temps. The TDP for the E8500 is 65W so is that what determines the max core temp? I'm running overclocked right now so I'm probably running above TDP right now. Would the max core temp then change?

...

Power = voltage * current

You raise the voltage and current flow in the IC also increases -> the power goes up. They just correlate the power to the max temp that they believe will give them a ~3 year life (warranty). They do a lot of testing to get enough statistical info so that their failure rates before end of warranty are acceptably small (meaning they don't have to replace the chip).

MasterG · Sep 12, 2008

Most likely the temp sensors is stuck on the core. Run the sensor test RealTemp has.

That description was probably a bit vague. My temps aren't running at 95C (they're actually around 48C right now). What I mean is that in RealTemp, it keeps track of how close you are to the max core temp. This max core temp is set by default at 95C. This just seems ridiculous to me.

Power = voltage * current

You raise the voltage and current flow in the IC also increases -> the power goes up. They just correlate the power to the max temp that they believe will give them a ~3 year life (warranty). They do a lot of testing to get enough statistical info so that their failure rates before end of warranty are acceptably small (meaning they don't have to replace the chip).

So should I then plug that curve into Excel to calculate what the max temp truly should be?

The Coolest · Sep 12, 2008

Tjunction max is not TCase max. Intel has released official info regarding TJMax in 45nm chips.
For E8000 series it's 100C.

MasterG · Sep 12, 2008

The Coolest said:
For E8000 series it's 100C.

Maybe I can use mine to make Ramen? 100C is insane.

deeppow · Sep 12, 2008

MasterG said:
... 100C is insane.

Why?

necronic · Sep 20, 2008

The issue here is that you are misunderstanding the difference between Tcase and Tjunction. The listing in the Intel documentation is of the Tcase, whereas the temperatures listed in the Realtemp (or Coretemp for that matter) are Tjunction.

What is the difference?

Tcase is reported from a diode in between the two cores, I believe, close to the heatsink. This reports the outer temperature of the CPU, which is the lower temperature of the two. Tjunction is the internal temperature of a core, which usually runs ~15C hotter. I believe that the E8500 chips have a Tjunction max of 100C, with throttling occuring at 90. You'll notice that both real temp and core temp report 2 values for Tjunction, 1 for each core.

jason4207 · Sep 21, 2008

You are using an older version of RealTemp that has Tjmax listed at 95. It is 100 per the latest info released from Intel, and this is reflected in RealTemps w/ version 2.75+.

Yes, this is a high temp, but it is the max temp Intel has spec'd for it's core die temp before shut-down measures are taken.

Tj is Thermal junction which is inside the core of the chip. Tcase is the metal covering the chip or the IHS. There is a temperature gradient b/n these points. It is very hard to believe that the gradient would be 28*C, and that is one aspect of the Intel specs that is very confusing. However, if you read the 72*C spec closely it is based on the TDP, and may not represent all conditions.

PwNZoRNooB · Sep 21, 2008

If it would be 72c it would be weird because my friend fries his E8500 @ 83c

(While benching with some nice clocks on AIR

)

bing · Sep 21, 2008

Well, if you have the gut, try this to find out your max temp "sweet spot" -> HERE, oh yeah, dont forget to read the warning 1st !

.

karkas · Sep 21, 2008

bing said:
Well, if you have the gut, try this to find out your max temp "sweet spot" -> HERE, oh yeah, dont forget to read the warning 1st !
.

I don't really see what finding your throttle point does for you? If your CPU doesn't throttle until 105C, this doesn't mean you can safely run your CPU at a higher temp.

Let me know if I'm missing something :santa2:

jason4207 · Sep 22, 2008

karkas said:
I don't really see what finding your throttle point does for you? If your CPU doesn't throttle until 105C, this doesn't mean you can safely run your CPU at a higher temp.

Let me know if I'm missing something

Your CPU will throttle at whatever temp you set Tjmax to. If you set Tjmax to 50 then your CPU will appear to throttle at that temp. Your CPU has no idea what the actual temps are...it just knows that when DTS=0, it's time to shut-down.

E8500 Max Temp

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