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Temperature sensor (diodes)

post #1 of 17
Thread Starter 
Ever since the advent of programs like Everest and CoreTemp, we've become aware that there are actually two types of thermal sensors from which the motherboard reports CPU temperatures. There is the sensor mounted in the motherboard socket (generally called "CPU Temp" by these programs), then there are the core temp sensors (thermal sensor diodes) which report the temperature dissipated by the processor core(s).

Here are a couple questions for true experts: 1) Where on the CPU die are these thermal diode sensors mounted in AMD CPUs, and 2) Can we take it for granted that these are all calibrated properly in all examples of CPUs off the line?

Question 2 seems really important, at least to me, because it's one thing to observe a temperature report (i.e., with software like the BIOS or CoreTemp or SpeedFan or Everest), and it's a whole other thing to see the effects of bad thermal dissipation (slowdowns, system instability, component failure, etc.).

I've got a feeling that there are CPUs with sensors that report either optimistically (too low) or pessimistically (too high).

Opinions? Comments?
    
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post #2 of 17
I looked at PC Wizard 2007 which reads from the diode in AMD cores.

I get around 1-2C above ambient. About 7C above ambient at load.

Stock clocks with a better than stock cooler, lapped both with a good application of AS5...

Well, Coretemp told me 50C. My heatsink isn't even that warm to the touch but it blows warm air through the fins. I have better airflow now too...

I don't want to believe CoreTemp but meh.
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post #3 of 17
Thread Starter 
Quote:
Originally Posted by standard235 View Post
I looked at PC Wizard 2007 which reads from the diode in AMD cores.

I get around 1-2C above ambient. About 7C above ambient at load.

Stock clocks with a better than stock cooler, lapped both with a good application of AS5...

Well, Coretemp told me 50C. My heatsink isn't even that warm to the touch but it blows warm air through the fins. I have better airflow now too...

I don't want to believe CoreTemp but meh.
Thanks for the input!

What I'm understanding from your comments is that different programs "report" different temperatures, yes? (Was the CoreTemp reading observed during max load conditions or idle? I wasn't clear about this.)

It's an interesting point to consider, though, if different programs read and report differently, even if they are reading from the same source (i.e., the thermal diode sensor). What might account for the discrepancies?

Moreover, there's the bigger question: Short of using a thermal sensing gun (or any other similar thermal measurement apparatus), how do we know how well the processor thermal sensors are calibrated?
    
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post #4 of 17
That's the thing. We trust these programs...

All my temps are usually load temps with Folding running...

Hmm. Hold on a sec. I'll check some stuff out. I was running at 2.5ghz with Clockgen Prime stable...
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post #5 of 17

Shot with unknown at 1969-12-31

That's Folding load temperatures at 2.2ghz, mem at DDR400 2.5-3-3-6.

My ambients are 73Fin the dining room. We have a window fan pulling in 69F air to my left about 8ft away. My case has 2 80mm intake with one in the bottom, one under CPU duct with flare taken off. The 3rd 80mm is at the end of the 5.25" bay blowing air onto my RAM/mobo.

My HDD isn't directly in the path of the 80mm fan either.

Trying to get all the info I can. I'll get some 2.5ghz load temperatures and take another likewise screenshot and report back...
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post #6 of 17
I guess noone is interested in this thread but I have another Folding load temp set. I don't know what ambients are but here it is.



2.585ghz with Folding at 100%.
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post #7 of 17
Thread Starter 
Quote:
Originally Posted by standard235 View Post
I guess noone is interested in this thread but I have another Folding load temp set. I don't know what ambients are but here it is.

2.585ghz with Folding at 100%.
Actually, I am very interested. And I'm very very grateful for your contributions, indeed.

Your most recent screenshot doesn't look like it's got temp readings from PC Wizard, though. (Or am I blind and just can't see them?)

But do CoreTemp and PC Wizard report the same temps?

Thanks again for your inputs!
    
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post #8 of 17
You raise some really interesting questions in this thread, I was wondering things of the same nature. I would like to know what temps do you worry about more your core temp or cpu temp? I have core temp and everest both running now, core temp gives me 29/31 and everest 30/32.
    
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post #9 of 17
Haha ***. I completely forgot.... hmm..

Well, my computer was in standby with fans on all night so let me Prime it and get it warm and then let it stabilize and I will get some temps.

I don't like you CoreTemp! I think it reports from the socket. CoreTemp is always close to my socket temp in PC Wizard...



Just a theory... but Core Temp looks to be around the socket temp in PC Wizard +8 Celcius,


Only because temperatures work on percentage terms and I'm in a completely different environment. My first 2 posts with screenshots were at my house in 73F
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post #10 of 17
My Core temps are quite odd. There are 2 of them in core temp, I assume one for each core. One core is about 6-8C higher than the other in most cases, I don't know why.

Speedfan reports a single core temp however, and a CPU temp, with the core temp being the highest.

I remember a while ago with the old socket-A chips, I had a proper temperature sensor that I stuck of the bottom of the CPU (when there were only 400 or so pins), and ran the cable inbetween the pins. I noticed that reported a temperature about 1-2C lower than the CPU temps, but this was before core temp and other such programs were released. So I think it is safe to say the CPU temperature's are accurate, for the socket-A chips anyway.

I am unsure about the accuracy of the core temps though, we can't exactly stick thermal probes inside the core.
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