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Strange temp readout on Q6600 @ 3.4 GHz

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December 10, 2008 10:43:23 AM

I overclocked my Q6600 to 3.4 GHz (426x8) and run stable 24+ hours under prime95...
But the temperatures on the 4 cores are different in 2x2 fashion... Namely first 2 cores (0 & 1) are running @ 66 deg at most while at the same time other 2 cores (2 & 3) are running @ 61 deg...
This difference is constant always - during stress-test or gaming... when idle the difference is bit less (2-3 deg)
Is this normal?

Ah, yes, the heat sink is Thermalright IFH-14...

Initially I thought that I have applied the thermal paste (the one which comes with zalman cooler) wrongly because I have this "big" difference... I reinstalled the heat sink again and also used another thermal paste (Innovation Cooling Diamond 7 Carat - very good paste - temp. drops from 72+ to ~66 deg), but I still have this difference in temperature.

any idea why? is the contact surface of the heat sink I need to check (maybe lapping the heat sink)?

thanks!
December 10, 2008 11:06:36 AM

It is perfectly normal, but I don't remember why it happens.
a c 172 à CPUs
a c 197 K Overclocking
December 10, 2008 11:34:22 AM

My Q6600 does the same thing. I get 61/65C at 3.6 GHz at 1.42 volts with a handlapped TRUE in an Antec 900 case. Remember, a Q6600 is two E6600 cores "glued" together and I doubt if Intel took the time and trouble to thermally match both cores.

Don't worry about it.
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December 10, 2008 11:57:04 AM

Yup, Ditto above. Completely normal. The cores are maufactured to a certain tolerance so your not going to get 2 identical cores so the power usage and temp output on each core will be slightly different.
December 10, 2008 12:32:15 PM

Thanks folks... :) 
I know that Q6600 is 2xE6600 under the hood, so indeed it is not big surprise to have some difference, but I didn't expect such big difference. That is why I asked...

@zipzoomflyhigh:
guess what - my nick name is "stupido" thus I'm no brainer... :pt1cable:  and I know that not all programs use all 4 cores and that is why I use prime95 to test my overclock... on all 4 cores... :bounce: 
and still I find it strange to have such a big difference. But thanks to the jsc & m_silkstone I have better understanding... so thanks for nothing to you... :hello: 
December 10, 2008 12:45:23 PM

There could also be a difference in the calibration of the thermal sensors for each pair of cores. The bottom line is that your temps are good for a Q6600 @ 3.4 GHz.
a b à CPUs
a b K Overclocking
December 10, 2008 6:32:56 PM

Stupido,

Your Q6600 is not properly calibrated.

Q6600 B3 = 2 x E6600 B2
Q6600 G0 = 2 x E6850 G0

Q6600 G0 Thermal Specification is 71c, which is CPU temperature, not Core temperature. This is a very common misconception.

Q6600 G0 from Intel's Processor Spec Finder - http://processorfinder.intel.com/details.aspx?sSpec=SLA...

Core temperature is 5c higher than CPU temperature at full load. See Page 4, Figure 5 in the following Intel document - http://arxiv.org/ftp/arxiv/papers/0709/0709.1861.pdf

From the Core 2 Quad and Duo Temperature Guide - http://www.tomshardware.com/forum/221745-29-core-quad-t...

Section 6: Scale

Scale 2: Quad
Q9x50: Tcase Max 71c, Stepping E0, TDP 95W, Idle 16W
Q9x50: Tcase Max 71c, Stepping C1, TDP 95W, Idle 16W
Q9400: Tcase Max 71c, Stepping R0, TDP 95W, Idle 16W
Q9300: Tcase Max 71c, Stepping M1, TDP 95W, Idle 16W
Q8200: Tcase Max 71c, Stepping M1, TDP 95W, Idle 16W
Q8200: Tcase Max 71c, Stepping R0, TDP 95W, Idle 16W
Q6x00: Tcase Max 71c, Stepping G0, TDP 95W, Idle 16W<--Q6600 G0

-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

Tcase = CPU temperature
Tjunction = Core temperature

You can calibrate your CPU temperature and individual Core temperatures by using Section 9 in the Guide.

Comp :sol: 
!