Originally Posted by sumitlian
Agree with you. I believe on BIOS readings too. And hence I did an experiment with my system. There is a setting in BIOS where I can set alarm at some certain CPU temp values. Available options are 60c, 70c, 80c and 90c. To test I set it to 60c. Then I increased vcore to 1.60v at 4.0Ghz and put my CPU in load in Prime95. I saw there was a buzzer sound coming from motherboard's MIC at exactly when Hardware Monitor's TMPIN1 reaches to 60c. This proves that the reading of Hardware Monitor's TMPIN1 = SpeedFan's Temp2 = BIOS readings = other utility's equivalent readings.
And as you should know BIOS developers follow the AMD's Bios and Kernal Developer's method. And in 'Bios and Kernal Developer's Guide', there is only one thing that is called as Tctl (Critical temp). And 70c is the max Tctl temp where BIOS has been configured to force the CPU to throttle down to lower frequency and lower voltage.
And hence I believe 70c can be considered as max temp for AMD CPU. Obviously semiconductors in the CPU will not burn at these temps as 97c+ is known for decaying silicon material. But AMD really don't want anyone going ever near that extreme temp. That is why they stated as 70c max critical.
However if you disable the Hardware Thermal Control (for Gigabyte), Over current/Over voltage protections (for Asus and Asrock) in the BIOS. Then I think we can take our CPU to 70c+. And yeah this will be foolish.
As the tech rep pointed out when they set the max safe operating temp to Tcas=70C on the 6100 or Tcase whatever on other chips they're being conservative and allowing a margin over that. Which means it can be pushed past but probably not advisable
As for Tctl, it's not an actual reading from a temperature probe/diode. Here's how AMD explains it:
"As for Tctl, there is a technical definition at http://support.amd.com/us/Processor_TechDocs/41256.pdf
on page 73 that (tries to) explain it. As a very crude Cole's Notes version, it doesn't measure temperature as much as it is a sliding scale that refers to the processor's current temperature as it relates to the temperature at which the cooling fan has to get to 100% to hit the maximum case temperature (TCaseMax). Confusing I know, but it allows the system to see how close it is to hitting 100% and subsequently it has to start slowing things down to get the temperature down. It is usually close to Tcase Max, but is more a point of reference for how close it is getting to Tcase Max, or if it is past that point and by how much. Things run normally at Tctl < TCaseMax - 0.125, and when it hits TCaseMax or higher, then things start getting shut down/slowed down/etc to get the temperature down. I hope that makes some semblance of sense, as it took a bit to wrap my head around it." (From the first tech support response I received)
As they explain it Tctl max is more like a point set before reaching Tcase max where the CPU starts to get throttled down.Edited by Bubba Hotepp - 5/16/12 at 4:10pm