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CPU Core Temp differences!

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August 12, 2008 11:07:06 AM

Hi,

I just recently build my new PC using:

Asus P5Q
Q6600 G0
Xigmatek hdt-s1283
4870
4GB Corsair XMS2 RAM

I want to overclock the CPU to around 3GHZ but even on stock the differences in temperatures between the cores is quite high.


Here you can see that at idle there is a difference of 10oC between core 0 and core 2.





This picture shows it under load using Prime 95 Small FFTs, as you can see there is a difference of 5oC between Core 0 and Core 2.


Because of this I have a few questions:

1) Is this "normal" or does it indicate any problems with the CPU or heatsink?
2) Which of the Four temperature monitoring programs should I believe as three of them are nearly the same but realtemp always reads slightly lower.
3) Are my temps alright for a mild overclock to 3ghz?

Thanks for your help.
August 12, 2008 11:31:30 AM

RealTemp is the most accurate and yes, the last two cores are always cooler than the first two
a b à CPUs
August 12, 2008 11:39:43 AM

^^ All programs that moniter the CPU temp have to "guess" at the temperature, but its been proven that core temp guesses too high. Use realtemp instead.

And yes, the last two cores are usually 5 degrees cooler.
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August 12, 2008 4:53:38 PM

Thanks for the replies and for clearing up my doubts about my CPU. Though it is a large difference the temps still are fine so I am happy with it. Monitoring wise are you sure real temp is the most accurate? As Speedfan, coretemp and HWmonitor all read higher temps than it. So those three are wrong and realtemp is correct?

Thanks again guys!
a b à CPUs
August 12, 2008 5:09:32 PM

Realtemp is correct. There was a massive 77 page thread on xtremesystems a while back (I think the creator of Realtemp still points to that thread) where he showed all the research that went into realtemp.

HWMoniter, Coretemp, and Speedfan all read too high. Realtemp reads correctly.
August 12, 2008 9:31:57 PM

gamerk316 said:
Realtemp is correct. There was a massive 77 page thread on xtremesystems a while back (I think the creator of Realtemp still points to that thread) where he showed all the research that went into realtemp.

HWMoniter, Coretemp, and Speedfan all read too high. Realtemp reads correctly.


Thanks this is good news as its temps are quite abit lower than Speedfans. I might even go for 3.4 now though I don't want my load temps to be over 60oC.
a b à CPUs
August 13, 2008 7:29:05 AM

thegodlikeone,

What you have described as "quite a bit lower" is actually 5c. SpeedFan uses Tjunction Max 100c, while Real Temp has proven that Tjunction Max 95c is correct for 65 nanometer G0 stepping processors, which applies to your Q6600.

Keep in mind that in addition to Core temperatures, SpeedFan also shows CPU temperature, and can be calibrated using my Core 2 Quad and Duo Temperature Guide: http://www.tomshardware.com/forum/221745-29-core-quad-t...

Concerning your desire to limit load temps to 60c, you should be aware as to how Intel defines processor Thermal Specifications. Understand that there are 2 sets of temps for all Core 2 processors; CPU temperature (Tcase), and Core temperatures (Tjunction).

Intel's Thermal Specification of 71c for the Q6600 G0, which is shown below in the Processor Spec Finder - http://processorfinder.intel.com/details.aspx?sSpec=SLA... - is for CPU temperature (Tcase), not Core temperature (Tjunction), which is a point that many users don't realize.



There is a known and consistent relationship between Tcase and Tjunction, which is 5c at stock settings under load, and is illustrated below from my Temp Guide:


Section 6: Scale

Scale 2: Quad
Q9x50: Tcase Max 71c, Stepping C1, TDP 95W, Idle 16W
Q9300: Tcase Max 71c, Stepping M1, TDP 95W, Idle 16W
Q6x00: Tcase Max 71c, Stepping G0, TDP 95W, Idle 16W

-Tcase/Tjunction-
--70--/--75--75--75--75-- Hot
--65--/--70--70--70--70-- Warm
--60--/--65--65--65--65-- Safe
--25--/--30--30--30--30-- Cool


As you can see, if you limit Core temperatures to 60c, then CPU temperature will be only 55c, which means that you will also be limiting your overclocking potential. I have conducted thermal testing on many Core 2 processors, just as the author of Real Temp has, so we're very familiar with their capabilities, as well as their specifications.

My point is that while I agree that cooler is better, don't underestimate the thermal tolerances of these processors, or the overclocking ability of the Q6600 G0, most of which will readily reach 3.6 with a high-end cooler. If you'd like to learn more about how temperatures work, then check out my Temp Guide.

Comp :sol: 
!