Is This Computer Reporting The Wrong Temperature?

By Mystic Mungis
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snaphat (Myles Landwehr) Member

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  On 11/01/2014 at 22:54, Boo Berry said:

Didn't older AMD CPUs (e.g. Phenom II's) report the wrong temperture? I remember hearing something like that, not sure.

Possibly on actual board probes, but doubtful on the CPU register. What I'd imagine happened is that software misinterpreted the CPU temperature register or other ACPI probes. I've definitely seen the latter (my Dell Core 2 laptop had this issue).

 

If there was a known CPU issue, we should be able to find it in AMD's errata list for their processors.

 

EDIT: Found a reference to K10s: http://en.wikipedia.org/wiki/Talk%3AAMD_K10#Unreliable_thermal_sensors.3F; http://support.amd.com/TechDocs/41322.PDF

 

EDIT2: I took a look and you are absolutely correct. This was for specific Phenoms, Phenom IIs, and Athlons.

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Mystic Mungis

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  On 11/01/2014 at 22:53, snaphat (Myles Landwehr) said:

I see, well do report back here if you find out which components are replaced.  (Y)

Aye Aye Captain!

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snaphat (Myles Landwehr) Member

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  On 11/01/2014 at 23:10, Boo Berry said:

I found this regarding AMD CPU temperatures (6 + 7).

 

EDIT: Apparently AMD's FM2 CPUs don't give accurate readings either.

 

Well there is a difference between the former and the latter. The temperature sensor is known to be completely unreliable in the K10s and acknowledged in the official errata (based on what I found in my edited post above). The temperature on the FM2 is just supposedly not as accurate as per core temperatures, which is what I've been saying. That doesn't mean that is completely wrong like the former. In a second, I'm going to try to check the FM2 errata and see if they list anything.

 

EDIT: Nope, I can't find any errata listed, so the FM2s temperature sensor is reliable if not particular accurate at temperature estimations.

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Mystic Mungis

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  On 11/01/2014 at 23:20, Boo Berry said:

Which honestly makes me glad I don't have an AMD CPU anymore. Good luck to the OP, hopefully the replacement will address your issue! :)

Thanks for the input :) This is actually for a friend, I'm buying the parts for my new rig on Friday and I'll be getting a Core i-5 3350p :P Thank you though!

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  On 11/01/2014 at 23:24, The Dingus Diddler said:

Thanks for the input :) This is actually for a friend, I'm buying the parts for my new rig on Friday and I'll be getting a Core i-5 3350p :p Thank you though!

Oh! Well in that case good luck for your friend and excellent choice for you. ;)

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snaphat (Myles Landwehr) Member

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  On 11/01/2014 at 23:24, The Dingus Diddler said:

Thanks for the input :) This is actually for a friend, I'm buying the parts for my new rig on Friday and I'll be getting a Core i-5 3350p :p Thank you though!

 

I think we can guarantee your core temps will say what they really are. But there is an important clarification here. In the case AMD K10s, this wasn't a random on/off manufacturing defect, this was a design issue that affected entire processor families until they fixed it. Such things are completely normal. Every processor design has errata because they are too complex to know exact operation even by the engineers who design them. The K10 hardware bug is an example of something that probably should have been found before manufacturing though. Seems to me that it would be obvious under stress testing. 

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  On 11/01/2014 at 20:24, snaphat (Myles Landwehr) said:
sniped

 

i know that the northbridge is part of the CPU die; it used to be a separate processor (combo with the southbridge) but not anymore, sorry if i didn't explain well. The fact here is that it's going to be hard to find the real cause of this problem. And the fact that the OP RMA'ed the whole computer would make very little possible to find if the CPU or the mainboard was the culprit.

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snaphat (Myles Landwehr) Member

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After thinking about it, i believe i can hazard a guess as to why the k10 temperature hardware bug wasn't found. The engineers probably use undocumented per core sensors during testing and didn't test the aggregate sensor on high loads. undocumented features wouldn't exactly be abnormal. One of the tricks hardware engineers do is implement processor features a few generations prior to an actual documented unveiling of said features. This way they can silently internally do testing on the features and fix any hardware bugs in them without the public ever knowing they existed. For example, I would be willing to bet that a number of "32-bit" x86 processors are actually 64-bit processors (with 64 bit bus lines, 64-bit decoders, etc.) with the 64-bit feature-set completely disabled. You wouldn't ever know because the microcode flashing of the processors that went for sale would disable all undocumented features. 

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  On 12/01/2014 at 01:16, snaphat (Myles Landwehr) said:

For example, I would be willing to bet that a number of "32-bit" x86 processors are actually 64-bit processors (with 64 bit bus lines, 64-bit decoders, etc.) with the 64-bit feature-set completely disabled. You wouldn't ever know because the microcode flashing of the processors that went for sale would disable all undocumented features. 

 

so very true.

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