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Core2Duo core temperature mystery

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December 20, 2006 4:45:39 AM

I have just built two PCs, both with the same CPUs C2D E6400, the same Mobos GA-965P-DS4, the same CPU cooler ARCTIC Freezer 7 PRO and the same 2x1GB DDR2 800MHz PC6400 CL5 KINGSTON DualChannel RAM. I have put them into two cases that are different brand but both with quite good ventilation. From my point of view, two identical PCs. What was my surprise when I found out that core temperature reported by CoreTemp differs by 10°C! I was even more surprised that VID is also different! Here are the figures:

Idle temp|Full-throttle temp|VID voltage
CPU1|52°C|66°C|1.275V
CPU2|42°C|57°C|1.325V

Both CPUs are overclocked to 2704MHz (FSB 338MHz) and run stabile.
There are basically 2 questions:

1. Can the core temperature differ so much in the two same CPUs or is it a temp probe error?

2. Why the CPU with highier voltage reports lower temperature as seems to me that opposite would be more natural?

Thanks.
December 20, 2006 5:05:54 AM

Quote:
I have just built two PCs, both with the same CPUs C2D E6400, the same Mobos GA-965P-DS4, the same CPU cooler ARCTIC Freezer 7 PRO and the same 2x1GB DDR2 800MHz PC6400 CL5 KINGSTON DualChannel RAM. I have put them into two cases that are different brand but both with quite good ventilation. From my point of view, two identical PCs. What was my surprise when I found out that core temperature reported by CoreTemp differs by 10°C! I was even more surprised that VID is also different! Here are the figures:

Idle temp|Full-throttle temp|VID voltage
CPU1|52°C|66°C|1.275V
CPU2|42°C|57°C|1.325V

Both CPUs are overclocked to 2704MHz (FSB 338MHz) and run stabile.
There are basically 2 questions:

1. Can the core temperature differ so much in the two same CPUs or is it a temp probe error?

2. Why the CPU with highier voltage reports lower temperature as seems to me that opposite would be more natural?

Thanks.

Check your HSF's
The intel HSFs, and one or two of the aftermarket ones officially qualify as "notorious" for being easily mis-mounted, resulting in high temps. Even if you've built dozens of systems and are absolutrly, postively sure you got them on right. THG forums have been filled with the same C2D heat issues, which wind up being the HSFs. Even extremely experianced builders have put the HSFs on improperly. No ones fault, just a poor design.
December 20, 2006 5:31:17 AM

Sorry, I am rather new on this. What HSF stands for? Is it a CPU heatsink? Does your recommendation applies also to ARCTIC Freezer 7 PRO I am using?
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December 20, 2006 6:17:54 AM

HSF = HeatSink/Fan

I think the AC Freezer 7 Pro is a clip-on HSF (rather than one with a backplate it screws into) so the thing about getting it seated right probably applies.
December 20, 2006 6:28:32 AM

OK, I should re-check HSF installation then. If this does not help, should I try to swap CPUs between cases in order to localize whether it is a case or CPU problem?
And what about different VID voltage reported? Any ideas why it is not the same value for both CPUs? Cannot be the root cause of the problem?
December 21, 2006 8:31:13 PM

There is still one more mysterious thing. Why one of those CPUs reports VID 1.275V while the second one 1.325V? What is the cause of the difference? What impact could it have? Thanks.
!