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CPU Core 0 30-35 degrees hotter

RoastingPig

RoastingPig

macrumors 68000
Original poster
Jul 23, 2012
1,606
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SoCal
Just a Quick Question im on a 5.1 quad core 2.8 mac pro with istat and im wondering why my CPU Core 0 "runs at 136 degrees at idle" is always 30-35 degrees hotter than CPU A Tdiode wich runs at 98 degrees on idle and CPU Heatsink wich runs at 93 degrees on idle?
 
RoastingPig said:
Just a Quick Question im on a 5.1 quad core 2.8 mac pro with istat and im wondering why my CPU Core 0 "runs at 136 degrees at idle" is always 30-35 degrees hotter than CPU A Tdiode wich runs at 98 degrees on idle and CPU Heatsink wich runs at 93 degrees on idle?
Click to expand...

It could be any one or a combination of many things including:

  1. the accuracy of one or more sensors,
  2. the difference in placement of one or more sensors,
  3. the scheduler bias of one CPU over another,
  4. the heat sink fins are dirty in one area more than another,
  5. the thermal paste was applied differently on one or the other,
  6. the airflow volume favors one over the other.
and so on.

If I were to guess I would accuse numbers 1, 2, and 6 as being the most responsible - especially number 6. :) And you should be able to tell if it's number 6 I would think... After awhile number 6 will cause a number 4 condition to appear.
 
RoastingPig said:
Just a Quick Question im on a 5.1 quad core 2.8 mac pro with istat and im wondering why my CPU Core 0 "runs at 136 degrees at idle" is always 30-35 degrees hotter than CPU A Tdiode wich runs at 98 degrees on idle and CPU Heatsink wich runs at 93 degrees on idle?
Click to expand...

This sounds like it may be thermal paste.
 
Im coming towards the end of my applecare and i want at least one thing to get replaced never had too:)


huao.jpg


Here are the readings im getting
 
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RoastingPig said:
Any suggestions on what i should do?
Click to expand...

What exactly is the 'CPU0 Relative to...' reading?

I can't remember what mine is, but I noticed that it goes down as Tdiode rises.

I mostly pay attention to Temp Diode and individual Cores (readable using Temperature Montior app). I've no idea what this Relative reading is supposed to be. Hopefully someone on the forum has knowledge about this. I'd love to know.
 
Sometimes I see about a 20F difference between CPU A and B. Sometimes A is hotter, sometimes B. I've never had any problems with stability on my Mac Pro.
 
pastrychef said:
Sometimes I see about a 20F difference between CPU A and B. Sometimes A is hotter, sometimes B. I've never had any problems with stability on my Mac Pro.
Click to expand...

I don't know if the 'Relative' reading is to do with 2-processor setups. Mabye it is.
The OP and I are using single-processor Mac Pros. Yet we still get a temperature reading for this.
 
Studio K said:
What exactly is the 'CPU0 Relative to...' reading?

I can't remember what mine is, but I noticed that it goes down as Tdiode rises.

I mostly pay attention to Temp Diode and individual Cores (readable using Temperature Montior app). I've no idea what this Relative reading is supposed to be. Hopefully someone on the forum has knowledge about this. I'd love to know.
Click to expand...

What might make sense is "xxx Relative to Ambient" ... i.e. the temperature rise of the part over nominal.

Perhaps the OP can revisit that screen and see if it is possible to pull it wider to get the whole line of text.
 
hfg said:
What might make sense is "xxx Relative to Ambient" ... i.e. the temperature rise of the part over nominal.

Perhaps the OP can revisit that screen and see if it is possible to pull it wider to get the whole line of text.
Click to expand...

it says CPU A, Core 0 Relative to Prochot
 
RoastingPig said:
i have no clue but it has me worried :(
Click to expand...

Back in the Pentium days it was a CPU pin which would go active on "Processor Hot" ... perhaps Intel still uses that term (and pin) today?

The extreme temperature you are seeing only on one location, assuming all continues to run OK, sounds like a faulty sensor to me.
 
hfg said:
Back in the Pentium days it was a CPU pin which would go active on "Processor Hot" ... perhaps Intel still uses that term (and pin) today?

The extreme temperature you are seeing only on one location, assuming all continues to run OK, sounds like a faulty sensor to me.
Click to expand...

Perhaps the Relative to ProcHot is the number of Degrees F or C that you are FROM the maximum allowable temperature (TJmax?). My Prochot number DECREASES as my Tdiode increases.
That would put your T Diode's maximum 'safe' temperature at 234F (or 111C) more or less (91F + 143F). I presume that this is the temperature at which your system would shut itself down to prevent damage from overheating.

I always understood that anything above 100C was too hot.
If all of this is the case, then the high number that you see (for Relative to Prochot) is possibly a good thing.

Try stress-testing the CPU and see what the 'CPUA Relative' temperature does. Open Terminal and type: yes > /dev/null &

Do several of these until your CPU cores are being heavily utilised.
To stop the testing, type: killall yes
 
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When i stress the cpu and the temp rises the prochot goes down. I understand now thats how much more degress the cpu can handle...does anyone else have that feature i have the latest update to istat wich i think is 4.06

Studio K said:
Perhaps the Relative to ProcHot is the number of Degrees F or C that you are FROM the maximum allowable temperature (TJmax?). My Prochot number DECREASES as my Tdiode increases.
That would put your T Diode's maximum 'safe' temperature at 234F (or 111C) more or less (91F + 143F). I presume that this is the temperature at which your system would shut itself down to prevent damage from overheating.

I always understood that anything above 100C was too hot.
If all of this is the case, then the high number that you see (for Relative to Prochot) is possibly a good thing.

Try stress-testing the CPU and see what the 'CPUA Relative' temperature does. Open Terminal and type: yes > /dev/null &

Do several of these until your CPU cores are being heavily utilised.
To stop the testing, type: killall yes
Click to expand...
 
RoastingPig said:
When i stress the cpu and the temp rises the prochot goes down. I understand now thats how much more degress the cpu can handle...does anyone else have that feature i have the latest update to istat wich i think is 4.06
Click to expand...

What sort of temperatures did you see in iStat when stressing the cpu?
What was your CPU T diode? And what was the Relative to....?
 
Here are my Cinebench results.
My temperatures are higher than yours, so I am the one that needs to be concerned.
You topped out at 60C with no increase in fan speed.
I only STOPPED at 72C because the CPU fans were going faster. And because the test was short.
 

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I am paying close attention to my CPU temps because I've just replaced my W3520 processor with a W3570.
I am concerned that my choice of thermal paste and/or my method of applying it may be contributing to these higher temperatures.

I used Noctua NT-H1 paste.

I would like to see others in the forum who've swapped CPU's in their quad-core Mac Pros post their CPU temps and share their choice of thermal paste.
I'm beginning to wonder if Apple's thermal grease is particularly optimised to work with their heatsink. And that applying any other random thermal paste will not yield the same quality of cooling.

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RoastingPig said:
Just a Quick Question im on a 5.1 quad core 2.8 mac pro with istat and im wondering why my CPU Core 0 "runs at 136 degrees at idle" is always 30-35 degrees hotter than CPU A Tdiode wich runs at 98 degrees on idle and CPU Heatsink wich runs at 93 degrees on idle?
Click to expand...

Is your machine a quad-core? Your sig says 12-core.
I am a single processor, quad-core. Are you dual-processor?
 
I just picked up this quad from a friend on the cheap and intend to flip on a later date..my 12 core is for home use and on the version of istat i have on that machine that reading dosent even show up on the menus
 
RoastingPig said:
I just picked up this quad from a friend on the cheap and intend to flip on a later date..my 12 core is for home use and on the version of istat i have on that machine that reading dosent even show up on the menus
Click to expand...

I notice that all of your temperature readings are lower than mine. Ambient is lower and hard drives are all considerably lower.

My room termperature is 79-80F. What's it like where you live? Do you live in a cold climate?

--------
I can't imagine buying a 2010 Mac Pro 'on the cheap'? Mine's a 2009 I picked up used, but I still wouldn't say it was inexpensive. Just a lot less than it's original new price.
 
I got it for 700 ..im in L.A its pretty hot today like 90 but on average like 80 and in my room like 75


Studio K said:
I notice that all of your temperature readings are lower than mine. Ambient is lower and hard drives are all considerably lower.

My room termperature is 79-80F. What's it like where you live? Do you live in a cold climate?

--------
I can't imagine buying a 2010 Mac Pro 'on the cheap'? Mine's a 2009 I picked up used, but I still wouldn't say it was inexpensive. Just a lot less than it's original new price.
Click to expand...
 
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