CPU temp higher than Core Temp

O

Owskie

Limp Gawd
Joined
Oct 13, 2003
Messages
456
I've been overclocking my system and following the temperatures from Core Temp, CPUID Hardware Monitor and OCCT when I stress test.

However, I installed EVEREST today and I'm running a Prime 95 blend and getting this

CPU#1 - 43
CPU#2 - 43
CPU#3 - 43
CPU - 54

Why would by CPU temp be higher than my core temps, isn't it usually the other way around? Which temp should I be following?
 
Core temps are all that matter, CPU temp is for the socket and not the chip. mine sometimes reads at 203C and sometimes -50c etc etc, so, overall, don't bother with it.
 
BlueFireIce said:
Core temps are all that matter, CPU temp is for the socket and not the chip. mine sometimes reads at 203C and sometimes -50c etc etc, so, overall, don't bother with it.
Click to expand...

lol and i thought i was the only one with the psycho cpu temp sensor.. :p right when windows boots up and speedfan turns on my cpu temp shows up as -256 then +256 then goes back to 20C(even though its still wrong)
 
Don't rely on software monitoring. I remember Asus Probe reporting my old Pentium 4 in the days running at 1039'C. It was all bullocks though obviously, installed Speedfan and the temps were a bit modest with IDLE temp of 41'C.
 
sirmonkey1985 said:
lol and i thought i was the only one with the psycho cpu temp sensor.. :p right when windows boots up and speedfan turns on my cpu temp shows up as -256 then +256 then goes back to 20C(even though its still wrong)
Click to expand...

Lol, yeah, it use to be really bad , but seems to have gotten better, it's either right on (10-15c lower than core temps) or it's way off. At least it seems for my mobo.
 
All of the software except the stuff that reads the internal Digital Temp Sensors embedded in the cpu scan the machines hardware (normally the SMS buss) and has to guess at what sensor is connected to what and guess at a proper name for what it guesses that sensor is doing. Usually the programs do a fairly good job of figuring it out. But as per above sometimes they get it wrong and sometimes they report a sensor port that is connected to nothing which gives the absolutely insane temps.

And with the parts of the program that do read the DTS an accurate measurement depends on what the programmer (or user if the setting is available) has set for Tjmax (which really should be called Tprochot_trip ). Differing programs will sometimes have different settings for Tjmax as it vaires between processors and that will make the reported core temps different between different programs even when reading the same DTS data.
 
BillParrish said:
Differing programs will sometimes have different settings for Tjmax as it vaires between processors and that will make the reported core temps different between different programs even when reading the same DTS data.
Click to expand...
So that's why I keep telling that peoples shoud rely only on distance to TJMax (which is raw data coming from DTS) and keep it >20 for daily use and then forget about core temperatures. :)
But to be fair now Nehalem/Lynnfield have TJMax value written in MSR so no more guess for them.
 
Ops, sorry, I'll try to elaborate then. :)
Here's the basic formula that all software uses:
Reported Temperature = TJMax - Digital Sensor Reading

So what you see in Everest/SpeedFan/whatever monitoring software use that formula.
TJMax is an arbitrary value pulled from hat by Intel and even now it's not well documented or written in stone (at least for pre Nehalem/Lynnfield CPU's).
Digital sensor reading is the distance to TJMax and it's the only value which dictates your CPU thermal behavior (throttle or thermal shutdown).

2hs2eq9.jpg


Why I say that's the only one that matters is because you can manipulate your TJmax value whatever you like (put it high to scary you friends with high core values or put it low to impress them with very low core temperatures) but distance to TJMax would be the same always.
Below is an example with my E8400 and different TJMax values(100 for left and 90 for right). You see what is the only constant there don't you? :)

2rc0uma.jpg


I hope that's more clear now why that TJMax value doesn't matter. :)
 
Why would it show cpu cores below ambient at stock? That doesn't seem to make much sense!
 
Owskie said:
when i was at stock i had my temps at 15celcius
Click to expand...
Your "CPU" temperature, or your core temperatures? If it was your CPU temperature, then that's because it's a completely worthless number. If it was your core temperatures, then the sensors were probably not reporting accurately.
 
You can't. However, idle temperatures aren't important anyway, so it doesn't matter.
 
Well if it is reporting incorrect idle temperatures it is probably reporting incorrect load temperatures right?
 
Below 30C the sensors are not very accurate. Its one of the reasons we are mainly concerned about load temps. Bragging rights with the machine sitting doing nothing (which for a long time a lot of people here held a lot of stock in, and occasionly we still get a "it idles 3C over ambinet, yea me !" posts) are dubious at best.

You never told us what your cpu is so we are unable to recommend a Tjmax value .

Edit. AMD. eh. who knows. With cool and quiet running, no load, it could be those values are close to correct in a case with excellent airflow. Still should not be below room temp. Forget most of the above about Tjmax etc as it mainly applies to Intel CPUs.
 
Last edited:
Owskie said:
Well if it is reporting incorrect idle temperatures it is probably reporting incorrect load temperatures right?
Click to expand...
No. These sensors are calibrated to be accurate at the temperatures where the CPU's thermal protection features kick in, so the closer you get to that point, the more accurate the sensors will be.
BillParrish said:
You never told us what your cpu is so we are unable to recommend a Tjmax value .
Click to expand...
He has a Phenom II X3 720 BE as you can see from his screenshot above. There is no Tjmax since we're not dealing with an Intel CPU.
 
Just updated Bios, doesn't go below ambient anymore. :)

edit: scratch that, they still hit 17-18
 
Last edited:
BillParrish said:
Below 30C the sensors are not very accurate. Its one of the reasons we are mainly concerned about load temps. Bragging rights with the machine sitting doing nothing (which for a long time a lot of people here held a lot of stock in, and occasionly we still get a "it idles 3C over ambinet, yea me !" posts) are dubious at best.

You never told us what your cpu is so we are unable to recommend a Tjmax value .

Edit. AMD. eh. who knows. With cool and quiet running, no load, it could be those values are close to correct in a case with excellent airflow. Still should not be below room temp. Forget most of the above about Tjmax etc as it mainly applies to Intel CPUs.
Click to expand...

Even so, AMD or not, I don't really need to worry?
 
Zero82z said:
No. These sensors are calibrated to be accurate at the temperatures where the CPU's thermal protection features kick in, so the closer you get to that point, the more accurate the sensors will be.

He has a Phenom II X3 720 BE as you can see from his screenshot above. There is no Tjmax since we're not dealing with an Intel CPU.
Click to expand...

I thought that was only intel sensors?
 
It's an excerpt from CoreTemp author:
The Coolest said:
And regarding the low ambient it's because the Phenoms report CPU temps that are not "absolute" but they are with a certain - unknown offset, some people say that it's around 15-20C, differing between CPUs.
Click to expand...
 
You must log in or register to reply here.
Back
Top