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I7 920 temps: which should i be paying attention to?

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October 5, 2009 9:33:11 AM

so i'm in the process of overclocking. i've hit bclock of 175 and still stable without touching vcore. i know the i7 can reach temps up to around 80-85 max but i'm just wondering should i be looking at the cpu temp or the individual cpu core temps? because there's a huge discrepancy between the two. my cpu @ 3.7 is around 54C, but the core temps reach upper 60s/lower 70s. which should i be more concerned with?

also i've been pretty much just following the guide on these forums and haven't touched vcore yet, just wondering if it's safe to leave this on auto while i mess with the bclock? i thought i heard somewhere that the auto vcore runs higher than whats actually displayed in the bios and this could cause problems. but like i said i'm stable for now without even touching the vcore so i should be okay with just leaving this on auto right?

wanna try for 4ghz as it seems like this is easily doable with the dark knight but i don't wanna screw something up in the process...

edit: fwiw e-leet utility reads the vcore right now at 1.26 and since 1.375 is generally a safe voltage i'm assuming this is completely acceptable?

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October 5, 2009 9:38:23 AM

Since you read the Core i7 overclocking guide, I assume you have been to the Overclocking -> Intel section of the forum. Check the Core 2 and Core i7 Temperature Guide which can be found there as well.
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October 5, 2009 3:50:28 PM

acs24 said:
my cpu @ 3.7 is around 54C, but the core temps reach upper 60s/lower 70s. which should i be more concerned with?

acs24 said:
... haven't touched vcore yet ... auto vcore runs higher ... e-leet utility reads the vcore right now at 1.26 and since 1.375 is generally a safe voltage ...

acs24,

2nd question - Auto Vcore? Never overclock using auto Vcore. You already had enough information within your question to reason out the answer. 1.375 is Vcore Max according to Intel's specifications.

1st question - CPU temperature or Core temperature? Both. Core temperatures alone don't reveal the thermal "big picture". The discrepancy between the two is because CPU temperature is mis-coded in BIOS, which causes it to read too low. When properly calibrated, "mean" (average) Core temperatures should be 5c higher than CPU temperature during Prime95 Small FFT's. Read on...

Temperatures and overclocking are all about specifications, so it's very important to be specific. If we're not, then the topic makes about as much sense as comparing apples-to-oranges thermal fruit salad in a blender! :pt1cable:  My objective is to assure that enthusiasts understand Intel's specifications, standards and test methods, so they can better decide how to apply and manage their overclocking options.

From Intel's Processor Spec Finder - http://processorfinder.intel.com/List.aspx?ParentRadio=...

All Core i7 9xx variants:

Vcore Max 1.375v
Tcase Max (CPU temperature) 68c
Tjunction (Core temperature) 73c

From the Core i7 and Core 2 Temperature Guide - http://www.tomshardware.com/forum/221745-29-sticky-core...


"Section 1: Introduction

Core i and Core 2 processors have 2 different types of temperature sensors; a CPU case (not computer case) Thermal Diode centered under the Cores, and Digital Thermal Sensors located on each Core. The case Thermal Diode measures Tcase (Temperature case), which is CPU temperature, and the Digital Thermal Sensors measure Tjunction (Temperature junction), which is Core temperature. Since these sensors measure 2 distinct thermal levels, there is a 5c temperature difference between them, which is Tcase to Tjunction Gradient. Core i7’s / i5’s and Core 2 Quad’s have 1 Tcase and 4 Tjunction sensors, while Core 2 Duo's have 1 Tcase and 2 Tjunction sensors ...

... The monitoring utilities provided by motherboard manufacturers monitor CPU temperature, while some popular freeware utilities monitor Core temperatures ... Real Temp ... is recommended for users interested in monitoring Core temperatures only ... SpeedFan monitors Tcase (CPU temperature) and Tjunction (Core temperature) ... "


The Thermal Specification shown in Intel's Processor Spec Finder is Tcase Max (CPU) not Tjunction (Core), which is a very common misconception among most enthusiasts. Since there's a 5c gradient between the CPU sensor and the Core sensors, (shown in the following Intel document) - http://arxiv.org/ftp/arxiv/papers/0709/0709.1861.pdf - just add 5c to the value shown in the Spec Finder to determine the corresponding Core temperature, which is 73c for all Core i7 9xx variants.

Intel's second and frequently misunderstood Thermal Specification, Tjunction Max, (100c for all Core i7 9xx variants) applies to overtemp protection such as Throttle and Shutdown, so you don't toast your transistors. As such, any i7 9xx Core temperatures which exceed 73c should be considered "overtemp". Further, when specifications are exceeded, then processor degradation becomes a concern, which is explained in the following AnandTech article - http://anandtech.com/cpuchipsets/intel/showdoc.aspx?i=3...

Prime95 Small FFT's is the Standard for processor thermal testing, because it's a steady-state 100% workload which yields steady-state temperatures, whereas Blend is a memory cyclic workload which yields fluctuating processor temperatures. Small FFT's will reach 97% thermal saturation within 7 to 8 minutes, so a 10 minute test is adequate. Thermal testing should be conducted as close as possible to 22c (72f) Standard ambient, with case covers removed, the computer clear of any desk enclosures, and all fans at 100% RPM to eliminate cooling variables, and to produce consistent and repeatable results for comparisons. If the Gradient between CPU temperature and "mean" (average) Core temperature is not ~ 5c, then BIOS is incorrectly coded. CPU temperature and Core temperatures can be individually calibrated in SpeedFan by following the Calibrations Section in the Temperature Guide.

OCCT and Burn Test (reminiscent of TAT) use LinPack, which shows thermal signatures that resemble the ups and downs of a bad day on the stock market, and cycle between light workloads, through test segments which spray all processor registers with all one's, (100% thermal load is equal to 115% workload), and can push an overclocked i7 9xx with HT enabled at Vcore Max 1.375, right on past Tcase Max to ring the Tjunction Max bell like a fire alarm! :o 

Since there are very few applications or games that will spike, let alone sustain processor workloads beyond 70% to 85%, utilities which load all registers with all one's are not representative of real-world computing. While these utilities are certainly very useful for stability testing, they are inappropriate for thermal testing. The 3DMark benches are excellent for stability testing, as are applications for ripping and encoding.

To make sense of CPU temperature and Core temperature, compare them to a 4 cylinder car with 5 temperature guages; 4 of the guages are cyclinder head temperatures (closest to the heat source), and the 5th guage is the overall engine temperature, which is 5c lower than the other guages, and is the temperature guage with which we're all familiar. We know the red zone (hot) for the i7 9xx starts at 68c (Tcase Max) on the engine temp guage and 73c (Tjunction) on the cylinder head temp guages, but if we push the engine too hard and peg all the guages, (95c Tcase overtemp / 100c Tjunction Max) then the engine will shut down.

If you'd like to learn more about processor temperatures, then just click on the link in my signature.

Hope this helps,

Comp :sol: 
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June 10, 2010 12:33:44 AM

Thanks a lot for that useful information. I can't stop obsessing about my i7 930 temps, my idle temps average from 47-54 and under prime 95 it gets up to 78 but I am overclocked to 3.9ghz with hyperthreading. I also have a megahalems cooler with push pull, no matter what I do I cant get the temp down. These 1366 boards run hot.
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June 10, 2010 3:22:51 AM

Man, you gotta stop digging up these old threads.

What's your VCORE and VTT set at????


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June 14, 2010 6:40:53 AM

Hello, I know this thread is outdated, I'm hoping someone will respond to this. I have an i7 930 and my idle temps run high, around 50-55 for cores and 48 for tmpin0, 56 for tmpin1 and 48t forempin2 while running prime 95, its the core temps that idle high, 50-55. Anyway intel doesn't give a tjmax and I know the idle temps arent correct. Does anyone know the offset that I need to set my tjmax to? I really need to get an idea of my temps so I can start overclocking. Is it possible for me to find out how to adjust the offsets so I can view the correct temp?

Please let me know I have been going crazy, I went through the stock heatsink to a corsair h50 now im running a megahalems with push pull and my temps went down a bit but idle temps are too high and prime 95 temps are high as well.

let me know thanks!
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