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I5 3570k Prime95 Test run and Cpu Temps

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April 7, 2013 12:46:21 PM

So i ran Prime95 for 2 hours on the small fft torture test to see how my temps would hold up and what not. Im guessing the worker numbers are the cores? They all said pass through out all of them.

Getting my data from Hardware monitor

Core#0 had a max temp of 57c
Core#1 had a max temp of 60c
Core#2 had a max temp of 61c
Core#3 had a max temp of 56c
The package which im guessing is the cpu as a whole had a max temp of 60c

My idle temps are
Core#0 31-33c
Core#1 26-28c
Core#2 28-30c
Core#3 27-29c
Package 30-32c

Im using a tuniq tower 120, Pretty much just looking to see what you computer gurus out there think of these temps. Should i run a different test with prime 95?

Thanks in advance
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April 7, 2013 1:01:40 PM

Those Temp looking great & fine till upper 80s on load
As in normal daytoday use your cpu wont be stressed like prime95 tourture test.
You can also try running Linx or intel burn in test etc.
Thanks

Wrecklessrebel said:
Thanks for the reply Imomun. So was i right about the package though?

By the looks of it > Yes :lol: 
Enjoy
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April 7, 2013 1:33:13 PM

Thanks for the reply Imomun. So was i right about the package though?
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April 7, 2013 3:20:54 PM

The "Package" or CPU temperature is incorrect because it can not be higher than or equal to the Core temperatures.

Core temperature is measured by an array of 8 analog thermal diodes which monitor the "hot spots" on the surface of the Core, and vary according to task and load. The analog levels are then converted to digital (A to D) by the Digital Thermal Sensor (DTS) which output the highest temperature of the analog array. So 4 individual DTS outputs give us 4 individual Core temperatures.

CPU temperature is measured by a single analog thermal diode located within the lower layers of the substrate material at the center of the entire processor die. Since this sensor is not in relative proximity to the individual Cores, some heat is dissipated before reaching the CPU sensor, so there is a know 5C gradient between average Core temperature and CPU temperature, which is shown in this Intel White Paper: http://arxiv.org/ftp/arxiv/papers/0709/0709.1861.pdf

Further, the analog CPU temperature is converted to digital by the motherboard's Super I/O (Input / Output) chip, which is then calibrated by BIOS look-up tables, and is the CPU temperature we see in BIOS and in monitoring utilities provided by motherboard manufacturers, as well as freeware such as Hardware Monitor and SpeedFan. I prefer SpeedFan because I can calibrate all 5 temperatures.

Although individual Core temperature DTS sensors (factory calibrated by Intel) are more accurate at high temperatures for processor throttling and shutdown protection, there are known issues such as some Cores showing high Idle temperatures, or too much variation between neighboring Cores. However, CPU temperature is frequently inaccurate due to incorrectly coded BIOS look-up tables for processor variants, which is sometimes corrected by BIOS updates. Regardless, here's what you need to remember:

(1) Core temperature is higher than CPU temperature.
(2) CPU temperature is higher than Ambient temperature.

In your case, the CPU temperature is wrong by about 5C too high. Your average Core temperature with Prime95 Small FFT's (steady-state 100% workload ideal for thermal testing) is about 59C, so if your CPU temperature (60C) was properly calibrated, then it should correspondingly be 54C, or 5C lower than your average Core temperature.

At stock Vcore settings with high-end air cooling or liquid cooling, the CPU temperature should Idle just a degree or so above Ambient (case intake) temperature. As your lowest Core temperature at Idle is 27c, then your CPU temperature should be 22C, which would make your Ambient temperature about 21C.

Lastly, Intel's Thermal Specification - http://ark.intel.com/products/65520/Intel-Core-i5-3570K... - is CPU temperature, NOT Core temperature, which is largely misunderstood. For the i5 3570K, the spec is 67C so the corresponding Core temperature is 5C higher, or 72c.

Hope this helps,

Comp :sol: 
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April 7, 2013 3:36:07 PM

^ Bravo ^ in English OP is n-e-a-r-l-y perfect :lol: 
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April 7, 2013 5:31:16 PM

Thank you for all the helpful info compu, im not gonna lie i had to read it 3 times but i think i understand it all.
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April 7, 2013 6:01:09 PM

It seems that Intel's Thermal Specifications weren't written by engineers only; there had to be some lawyers from their legal department involved, which would explain why their specs are about as clear as mud. Having studied their specs and test methodologies, it's entirely over-complicated. I think it's amazing that they haven't rewritten the specs with an emphasis on Core temperatures rather than CPU temperature.

As such, it unfortunately requires some detailed explanation to make the differences between CPU temperature and Core temperature clear. If I hadn't offered thorough enough information, then it would never be understandable. Sorry if it's a little deep.

Was I correct about your Ambient temperature being about 21C ?
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April 7, 2013 8:47:32 PM

yep you were close man, another question i have is if theres any other temp sensor in there to monitor ambient temp or intake air temp? I see it has systin and cputin readings for temp.
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April 7, 2013 9:29:01 PM

There are seldom any sensors for Ambient temperature. The best way to measure Ambient is to place a trusted analog or digital thermometer near your computer's air intake. Other than the single CPU sensor and the individual Core sensors, there are no other sensors for the processor, however, there is typically a sensor for the motherboard's Northbridge and Southbridge chipsets, or the Platform Controller Hub (PCH) chipset. Hard drives and SSD's also have temperature sensors.
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April 15, 2013 1:07:19 PM

Ok Computronix i went out and bought a temp sensor so i could do some checking. I ran prime95 for a little over an hour. and here where my results


The ambient temp in my room was about 25c at the time of testing. I have a Thermaltake Chaser MK-I case with 4 200mm fans. 2 top exhaust, side and front intake.

Now my bios is out of date by 1 version and i tried to dl the file to update it but the file is a .cap file and i cant figure out how to install or update it.

The description for the bios update was "Fix WINPE UEFI mode can't boot" so could they even have temp sensor updates or whatnot?

As always any insight to any of this would be great :) 
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April 17, 2013 11:24:39 AM

Sorry it took me so long to respond.

In Hardware Monitor, "Package" is following the highest Core temperature, while "CPUTIN" is CPU temperature. In SpeedFan, "Temperature 2 offset"
is CPU temperature. As I mentioned in my first answer, I use SpeedFan because I can calibrate all five temperatures (the single CPU temperature and the 4 individual Core temperatures). Although BIOS updates often include undocumented fixes, I wouldn't depend upon an update to correct inaccurate CPU temperature.

When Intel conducts thermal testing in their labs, (which is detailed in their White Papers), it's under tightly controlled environmental conditions (22.0C / 71.6F). A groove is cut into the Integrated Heat Spreader (IHS) where a thermocouple is embedded in the center, then the stock cooler is attached, and a steady-state 100% workload is run. This in turn yields a steady temperature after thermal saturation is reached, which requires less than 10 minutes.

Since the thermocouple is highly accurate, Intel's Thermal Specification, (shown as "Tcase"), is expressed to the tenth of a degree, which for the i5 3570K, is 67.4C. As the thermocouple is used for lab testing only, the single Analog Thermal Diode (positioned in the center of the processor die within the lower layers of the substrate material) is used instead to "emulate" a laboratory thermocouple. The accuracy of the emulation (CPU temperature) is determined by the "look-up" tables in BIOS, which is all too often mis-coded for many socket 775, 1155, 1366 and 2011 processor variants.

As neither the single Analog Thermal Diode (CPU temperature) or the individual Digital Thermal Sensor (DTS) for each of the 4 Cores is not as accurate as a thermocouple, the specification for Tjunction Max is expressed as a whole number, rather than to the tenth of a degree, which for the i5 3570K, is 105C (shutdown temperature).

Observing Intel's 67.4C Tcase specification, we simply add 5C for the thermal gradient offset (shown in Intel's White Papers) to convert from Tcase (CPU temperature) to Tjunction (Core temperature), then we have 72.4C as an equivalent Core temperature to Intel's lab tests. If your Ambient temperature was below or above 22C when you tested your rig, then remember to add or subtract the difference to correct your test results for 22C Standard Ambient.

Ambient = 22C
Tcase Spec (CPU temp) 67.4C
Gradient Offset +5C
Tjunction (Core temp) = 72.4C
Tj Max Spec (Shutdown temp) 105C

When we consider overclocking, all experienced overclockers know that a cooler processor is a more stable processor. When corrected to 22C Ambient after running Prime95 Small FFT's, I can never, in good conscience, recommend Core temperatures higher than 75 ish. Excessive heat kills electronics. Personally, I believe that 80C and up is just too hot for sustained operation and longevity for CPU's, as well as GPU's.

Some additional guidelines for the benefit of others who may read this:

All Core 2 and Core i generation processors - do not exceed 75C.
1st generation Core 2 processors 65 nanometer - do not exceed 1.5 Vcore.
2nd generation Core 2 processors 45 nanometer - do not exceed 1.4 Vcore.
1st generation Core i processors 45 nanometer - do not exceed 1.4 Vcore
2nd generation Core i processors 32 nanometer - do not exceed 1.35 Vcore.
3rd generation Core i processors 22 nanometer - do not exceed 1.3 Vcore.

The bottom line is that although your CPU temperature is inaccurate, and would be 5C below "average" Core temperature if it had the correct look-up tables in BIOS, your Core temperatures are normal for "high-end" air cooling at stock clock. You won't see higher temperatures until you overclock enough to require a higher Core voltage.

For example, Intel's Thermal Specification for my i7 2700K is 72.6C, which would make my "do not exceed" Core temperature 77.6c. As you can see in my signature below, I've pushed my Vcore to the limit and my Core temperatures about as high as I care to go, which gives me a stable 4.8 Ghz overclock for a 12 hour run of Prime95 Small FFT's. It's all about understanding the specifications.

Hope this provides additional clarification,

Comp :sol: 
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April 17, 2013 3:04:45 PM

No problem for the wait on the reply man we all have other things to attend to at times. Again your full of information lol, reading through your posts has given me a much greater understanding of cpu and core temps. I will have to try out speed fan and see how i like it.

Is it difficult to calibrate your temps on speed fan ? I really don't plan on overclocking for awhile until ive gathered enough knowledge to where i think i can go for it successfully.
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April 17, 2013 3:13:14 PM

SpeedFan is not for the squeamish. It has a considerable learning curve, but once you get it set up, it's really sweet. I especially like the "Charts" feature and find it extremely useful to visualize temperatures and Vcore. If you have your fan headers connected to the motherboard, then SpeedFan can throttle your fans so they only spin up high when your rig is under heavy load, so that most of the time, your rig is very quiet.
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