Intel TAT / CoreTemp / IDCC all different temperatures....

[SLi_dog]

If you ever did DIY in electronic or experiment by using common diode as temp probe, and more than one of course, you will know that the offset deviations for diodes as I mentioned at my previous post rougly hovering about + or - 15 to 20 C. Voila !

So simple conclusion, the accuracy for any uncalibrated diode as a temp probe is about +/- 15 to 20 C.

In the worst case scenario, if they're off by even - 20C, meaning the cpu is actually hotter 20C more than the reported temp by the tdiode, still the cpu is in the safety margin/limit before the thermal/throttling mechanism kicks in.

A +/- 20C error margin is damn scary. That would be a worse case senario though yeah? I'd hope that Intel used used better diodes than that
That said, the accuracy of the diode is not something we as end users can control and if it was misreading, it would affect the CPU as it approached the throttle point regardless of whether it was overclocked or not so it kinda a mute point to me

Now other view angle, that crappy Intel stock HSF thermal resistance at full speed fan is 0.2 C/W. (this is the official number from their datasheet too)

OT, I hate that these days, popular HSF makers don't like to mention this very important specification (C/W) in their product anymore like in the old day.

Now the calculation as usual and using 130 Watt power dissipation :

IHS Temp = (Ambient Temp) + ( (Heatsink C/W) X (Power Dissipation) )

hence

IHS Temp = (Ambient Temp) + ( 0.2 C/W X 130 Watts) = Ambient Temp + 26 C

So "on paper" the max. ambient temperature for this QX6800 beast using stock HSF at 130 Watt full load is at 28.8 C

Of course we all know this is strictly "on paper", real life those limits are much higher and more relax since they just want to play it safe at the "official" paper.

hmm interesting.

I'm quite confident that they (Intel) is also making a safe and calculated assumption like this :

Ignore or don't care at the tdiode values, with a cpu running "at stock speed/not OCed", with stock Intel HSF, and at full load in the room temp as high as 30 C, it is very safe to assume that the CPU is still on safe temp limit.

Don't you agree ?


This is how I see this overall issue.

I do agree that Intel likely aren't that concerned about whether the diode is that accurate because they've built in a fair amount of headroom.
However, if you replace the stock intel HSF with a good quality one and reduce the vcore to only what the CPU needs, you may be able to keep within or below this headroom even when overclocked.

• Example 1: A Q6600 at 2.4Ghz, on the stock Intel HSF, in a poorly ventilated case, with auto set vcore (usually around 1.35v) might have max load temps of 20C from the DTS = 0C point.
  
  
• Example 2: The same Q6600 at 3Ghz, on a Tuniq Tower, in a well ventilated case, with 1.21vcore might also have max load temps of 20C from the DTS = 0C point.

I don't see how one is worse than the other? I'm actually more inclined to believe that the second example is better for the CPU as it uses less voltage which reduces electron migration.