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Intel Temperature Guide

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  • CPUs
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a b K Overclocking
a b à CPUs
14 September 2013 03:46:37

Intel Temperature Guide - by CompuTronix

Rev. 40808


Preface

The purpose of this Guide is to provide an understanding of standards, specifications, thermal relationships and test methods so that temperatures can be uniformly tested and evaluated. This Guide supports Core i and Core 2 desktop processors.


Sections

1 - Introduction
2 - Ambient Temperature
3 - CPU Temperature
4 - Package Temperature
5 - Core Temperature
6 - Throttle Temperature
7 - Relative Temperatures
8 - Overclocking and Vcore
9 - The 22 Nanometer Problem
10 - Software Tools
11 - Thermal Testing @ 100% Workload
12 - Thermal Testing @ Idle
13 - Improving Temperatures
14 - Summary
15 - Intel Processor Temperature FAQ


Section 1 - Introduction

Whether you overclock or not, processor temperatures continue to be a major source of confusion and debate. Intel's Thermal Specification for each processor variant is shown as "Tcase". Although this specification may seem simple enough, the technical details are somewhat complicated.

Intel desktop processors have a single Analog sensor (CPU temperature) and each Core has a Digital sensor (Core temperature). There are 3 thermal sensors in a Dual Core, 5 in a Quad Core and 7 in a Hex Core. In order to get a clear perspective of processor temperatures, it's important to understand the terminology and specifications, so we'll begin with Ambient temperature.


Section 2 - Ambient Temperature

Also called "room" temperature, this is the temperature measured at your computer's air intake. Standard Ambient temperature is 22C. This is a very critical measurement, because Ambient directly affects all computer temperatures. Use a trusted analog, digital or IR thermometer to measure Ambient temperature.

Here's the temperature conversions and a short scale:

Cx9/5+32=F ... or ... F-32/9x5=C ... or more simply ... an increase of 1C = an increase of 1.8F

30.0C = 86.0F Hot
29.0C = 84.2F
28.0C = 82.4F
27.0C = 80.6F
26.0C = 78.8F Warm
25.0C = 77.0F
24.0C = 75.2F
23.0C = 73.4F
22.0C = 71.6F Standard ... or ... 22.2C = 72.0F
21.0C = 69.8F
20.0C = 68.0F Cool

As Ambient temperature increases, thermal headroom and overclocking potential decreases.


Section 3 - CPU Temperature

Also called "Tcase", this is the temperature shown in Intel's Thermal Specification - http://ark.intel.com/ It's measured on the surface of the Integrated Heat Spreader (IHS) under tightly controlled laboratory conditions at 22C Standard Ambient. For lab testing only, a groove is cut into the surface of the IHS where a thermocouple is embedded at the center. The stock cooler is seated and a steady-state 100% workload is applied. Peak temperature is reached within 10 minutes.

Since there's no thermocouple on any processors outside Intel's labs, a single Analog Thermal Diode located in the center under the Cores is used to substitute for a thermocouple. This sensor measures "CPU" temperature, which is the overall temperature of the processor. The Analog value is converted to Digital (A to D) by the Super I/O (Input / Output) chip on the motherboard, then is calibrated to look-up tables coded into BIOS for each socket-compatible processor.

CPU temperature in BIOS is higher than in Windows at Idle, because BIOS starts the processor at boot voltage to ensure that it can initialize under any conditions. The monitoring utilities provided by motherboard manufacturers on your Driver DVD reads CPU temperature. Thermal code can vary greatly between BIOS suppliers and version updates, and can be wrong by up to 30C. Don't expect BIOS or CPU temperature to be accurate.


Section 4 - Package Temperature

Applies to Core i processors only. Package temperature is shown in a few software utilities such as Hardware Monitor - http://www.cpuid.com/softwares/hwmonitor.html Package temperature is the hottest Core. It can be affected by Intel's on-Die Integrated Graphics Processor Unit (IGPU). Package temperature isn't critical.


Section 5 - Core Temperature

Also called "Tjunction", this is the temperature measured directly on the hot spots within each Core by individual Digital Thermal Sensors (DTS). Load temperatures in the mid 70's are safe. Although Core temperature sensors are factory calibrated by Intel, deviations between the highest and lowest Cores could be 10C. Sensors are designed to be more accurate at high temperatures to protect against thermal damage, so don't expect idle temperatures to be accurate.

Since the CPU sensor is located under the Cores, and not near the hot spots, there's a 5C thermal gradient or "offset" between Core temperature and CPU temperature. This is shown on Figure 5 in the following Intel document - http://arxiv.org/ftp/arxiv/papers/0709/0709.1861.pdf

At Default / Auto BIOS settings (stock clock and Vcore) with 100% workload on the stock cooler, Core temperature is 5C higher than the Tcase specification. This means that whatever the Tcase specification - http://ark.intel.com/ - is for your processor, just add 5C to get the corresponding value for Core temperature. Core temperatures respond instantly to changes in load.


Section 6 - Throttle Temperature

Also called "Tj Max" (Tjuction Max), this is the Thermal Specification that defines the Core temperature at which the processor will Throttle (reduce clock speed) to protect against thermal damage. Although Intel's Core i processors are capable of operating above 90C, we also know that excessive heat kills electronics. Sustained Core temperature greater than 80C is too hot for stable gaming or processor longevity.

Exception: Early 1st Generation Core 2 processors with stepping revisions B2 and B3 and have lower Tcase and TjMax specifications than other variants. Core temperatures on these processors should be kept under 70C.

Your highest temperatures occur during stability tests. Temperatures are lower during real-world everyday workloads such as processor intensive applications or gaming.


Section 7 - Relative Temperatures

The relationships between Ambient temperature, CPU temperatures, Core temperatures and Throttle temperatures are shown below for several popular Quad Core processors. All values are based on Intel documentation.

-> Core 2

1st Generation 65 Nanometer: Q6600 G0 (TDP 95W / Idle 16W)

Standard Ambient = 22C
Tcase (CPU temp) = 71C
CPU / Core offset + 5C
Tjunction (Core temp) = 76C
Tj Max (Throttle temp) = 100C

2nd Generation 45 Nanometer: Q9650 E0 (TDP 95W / Idle 16W)

Standard Ambient = 22C
Tcase (CPU temp) = 71C
CPU / Core offset + 5C
Tjunction (Core temp) = 76C
Tj Max (Throttle temp) = 100C

-> Core i

1st Generation 45 Nanometer: i7 920 D0 (TDP 130W / Idle 12W)

Standard Ambient = 22C
Tcase (CPU temp) = 67C
CPU / Core offset + 5C
Tjunction (Core temp) = 72C
Tj Max (Throttle temp) = 100C

2nd Generation 32 Nanometer: 2500K / 2600K (TDP 95W / Idle 8W)

Standard Ambient = 22C
Tcase (CPU temp) = 72C
CPU / Core offset + 5C
Tjunction (Core temp) = 77C
Tj Max (Throttle temp) = 98C

3rd Generation 22 Nanometer: 3570K / 3770K (TDP 77W / Idle 4W)

Standard Ambient = 22C
Tcase (CPU temp) = 67C
CPU / Core offset + 5C
Tjunction (Core temp) = 72C
Tj Max (Throttle temp) = 105C

4th Generation 22 Nanometer: 4670K / 4770K (TDP 84W / Idle 2W)
4th Generation 22 Nanometer: 4690K / 4790K (TDP 88W / Idle 2W)

Standard Ambient = 22C
Tcase (CPU temp) = 72C
CPU / Core offset + 5C
Tjunction (Core temp) = 77C
Tj Max (Throttle temp) = 100C

The Core temperatures above show that mid 70's are safe.


Section 8 - Overclocking and Vcore

Overclocked processors can reach up to 150% of their Thermal Design Power (TDP) when using manual Core voltage (Vcore) settings, so high-end air or liquid cooling is critical. Every processor is unique in it's overclocking potential, voltage tolerance and thermal behavior.

Regardless, excessive Vcore and temperatures will result in accelerated "Electromigration" - https://www.google.com/?gws_rd=ssl#q=Electromigration - which prematurely erodes the traces and junctions within the processor's layers and nano-circuits. This will eventually result in blue-screen crashes, which will become increasingly frequent over time.

CPU's become more susceptible to Electromigration with each Die-shrink, so 22 Nanometer architecture is less tolerant of over-volting. Nevertheless, Vcore settings should not exceed the following:

-> Core 2

1st. Generation 65 Nanometer ... 1.50 Vcore
2nd Generation 45 Nanometer ... 1.40 Vcore

-> Core i

1st. Generation 45 Nanometer ... 1.40 Vcore
2nd Generation 32 Nanometer ... 1.35 Vcore
3rd Generation 22 Nanometer ... 1.30 Vcore
4th Generation 22 Nanometer ... 1.30 Vcore

When tweaking your processor near it's highest overclock, keep in mind that for an increase of 100 MHz, a corresponding increase of approximately 40 to 50 millivolts (0.040 to 0.050) is required.

More about : intel temperature guide

a b K Overclocking
a b à CPUs
20 May 2014 04:21:42

Intel Temperature Guide - Continued


Section 9 - The 22 Nanometer Problem

Core i 3rd and 4th Generation processors are very sensitive to small increases in voltage and frequency. When overclocked, temperatures could rise above 90C, so high-end air or liquid cooling is critical. 22 Nanometer processors are more difficult to cool than previous Generations for three reasons:

(1) The 3rd and 4th Generation 22 Nanometer Die has 35% less surface area in contact with the underside of the Integrated Heat Spreader (IHS) than the 2nd Generation 32 Nanometer Die.

(2) 3rd and 4th Generation processors have over 20% more transistors packed into a smaller Die than 2nd Generation processors.

(3) 3rd and 4th Generation processors use Thermal Interface Material (TIM) between the top of the Die and the underside of the IHS instead of solder, which was used in 2nd Generation and earlier processors.

Since the bonding material which seals the perimeter of the IHS to the Substrate is slightly too thick, this tends to increase the space between the underside of the IHS and the Die, which can cause the TIM to compress unevenly. The effect of this manufacturing procedure is that many processors show a wide deviation between Core temperatures, or one Core which runs much hotter than it's neighbors.

This has encouraged some overclockers to "de-lid" or remove their processor's IHS, which basically involves thoroughly removing the bonding material, replacing only the TIM and then restoring the IHS. Typical results are significantly lower Core temperatures and less deviation between Cores. Here's an excellent YouTube - http://www.youtube.com/watch?v=XXs0I5kuoX4 - that shows before, how-to, and after, but beware that de-lidding will void your warranty, and it's not difficult to damage or destroy your processor.

Intel has addressed these thermal problems in their Haswell refresh. The Devil's Canyon processors have an improved IHS alloy and a new Polymer TIM. Although not as thermally efficient as solder, temperatures have been improved by several degrees.

Regardless, 4th Generation processors differ from their 3rd Generation counterparts in that they have a Fully Integrated Voltage Regulator (FIVR) on the Die, instead of on the motherboard. This increases their Thermal Design Power(TDP), so all other factors being equal, 4th Generation processors run hotter at 100% workload than any of their predecessors.


Section 10 - Software Tools

In order to properly test and evaluate your temperatures whether overclocked or not, you'll need to download the following freeware utilities:

CPU-Z - http://www.cpuid.com/softwares/cpu-z.html
Hardware Monitor - http://www.cpuid.com/softwares/hwmonitor.html
Prime95 v26.6 - http://windows-downloads-center.blogspot.com/2011/04/pr...
Real Temp - http://www.techpowerup.com/downloads/2089/real-temp-3-7...
SpeedFan - http://www.almico.com/sfdownload.php


Section 11 - Thermal Testing @ 100% Workload

We all remember science class where one of the basic principals for conducting any scientifically controlled experiment, is that it's critical to follow the same procedure every time. This eliminated variables so results will be consistent and repeatable. If everyone is testing their rigs with X stress software at Y Ambient temperature with Z measuring software, then it's impossible to compare apples to apples.

This is why processor temperatures continue to be a major source of confusion and debate. In this Section we'll explain how to properly test your rig. It's important to remember that we are not stress testing; we are thermal testing to produce a Core temperature benchmark.

Prime95 Small FFT's is the standard for CPU thermal testing, because it's a steady-state 100% workload. This is the test that Real Temp uses to test sensors. The link above is to version 26.6, which is well suited to all Core 2 and Core i variants.

Core i 2nd, 3rd and 4th Generation CPU's have AVX (Advanced Vector Extension) instruction sets. Recent versions of Prime95 run AVX code on the Floating Point Unit (FPU) math coprocessor, which produces unrealistically extreme temperatures. The FPU test in the software utility AIDA64 shows the same results.

It's not necessary to run AVX code for thermal testing. Prime95 v26.6 produces temperatures on 3rd and 4th Generation processors more consistent with 2nd Generation, which also have AVX instructions, but do not suffer from thermal extremes due to having a soldered Integrated Heat Spreader and a 35% larger Die.

Prime95's default test, Blend, is a cyclic workload for testing memory stability, and Large FFT's combines CPU and memory tests. As such, Blend and Large FFT's both have cyclic workloads which are unsuitable for CPU thermal testing.

Other stability tests such as Linpack and Intel Burn Test have cycles that load all registers with all one's, which is equivalent to a 110% workload, and are also unsuitable for CPU thermal testing. The software utility OCCT runs elements of Linpack and Prime95.

Shown above from left to right: Small FFT's, Blend, Linpack and Intel Burn Test.

Shown above from left to right: Small FFT's, Intel Extreme Tuning Utility CPU Test, and AIDA64 CPU Test.

The "Charts" in SpeedFan show how these tests create different thermal signatures. Intel Extreme Tuning Utility is also a cyclic workload. Although AIDA64's CPU test is steady-state, the workload is insufficient, and it's not available as freeware.

Setup:

Testing should be performed with your computer clear of desk enclosures or items that block airflow. Covers should be removed and all fans and circulating pump (if equipped with liquid cooling) at 100% RPM, so temperatures can be tested under ideal conditions.

Testing close to 22C Ambient is preferred so as to provide normal thermal headroom, but is not required. Testing at high Ambient temperatures should be avoided. If adequate A/C is unavailable, then test late at night or early in the morning when Ambient is lowest.

When performing a thermal test above 22C Ambient, remember to subtract the difference so that test results are corrected to Standard Ambient. This eliminates variables so results will be consistent and repeatable.

Example:

During Thermal Testing @ 100% Workload;

if measured Ambient is 25C, and reported Core temperature is 80C,
then at standard Ambient 22C, corrected Core temperature would be 77C.

Test:

Run Prime95 v26.6 Small FFT's for 10 minutes, then use your thermometer to measure Ambient. Use Real Temp to measure your Core temperatures. Correct your results to Standard Ambient.

Results:

Core temperatures should be in the mid 70's for most processor variants. However, depending on variables such as clock speed, Vcore, Ambient and cooling, Core i 3rd Generation, and especially 4th Generation temperatures could rise above 90C. Core temperatures in the mid 70's are safe during real-world everyday workloads.

Exception: Early Core 2 1st Generation processors with stepping revisions B2 and B3 and have lower Tcase and TjMax specifications than other variants. Core temperatures on these processors should be kept under 70C.

Deviations in sensor accuracy between individual Cores can be up to +/- 5C. This means there could be 10C between the highest and lowest Cores, so "average" Core temperature is often more realistic.


Section 12 - Thermal Testing @ Idle

Look closely at the SpeedFan Charts above, where idle temperatures are shown between load temperatures. Notice that some Cores have more "range" than others and idle lower. Sensors can be tested with Real Temp. Core temperature sensors are designed to be more accurate at high temperatures for Throttle protection, so don't expect idle temperatures to be accurate.

Remember that when you power up your rig from a cold start, all components are at Ambient, so temperatures can only go up. With conventional air or liquid cooling, no temperatures can be less than or equal to Ambient.

If "Speedstep", also called Enhanced Intel Speedstep Technology (EIST), is disabled in BIOS, then depending on Vcore and clock speed, idle Power can be nearly 40 Watts, which will result in high idle temperatures, especially when combined with high Ambient temperature.

Setup:

Speedstep and all "C" States (C1E on earlier motherboards) needs to be enabled to achieve the lowest possible idle temperatures. Also, if Windows Power Options is not set correctly, then Speedstep will not work.

To check this, click on Control Panel, Power Options, then to the right of the selected plan, click on Change plan setting. Next click on Change advanced power settings, then drag the scroll bar down. Click on + next to Processor power management, then click on + next to Minimum processor state. This Setting must be 5%. If it's not, then correct it and click Apply.

Restart into BIOS and confirm that you've saved your settings to a Profile. Change all settings to stock (Default / Auto) including SpeedStep, all C States and Vcore, then save and exit. Reboot into Windows and confirm that your rig is at dead idle; no programs running, and off line. No Folding or SETI or tray trash running in the background, and less than 2% CPU Usage under the "Performance" tab in Windows Task Manager.

Use CPU-Z to confirm that Core Voltage and Core Speed has decreased as follows:

-> Core 2

1st. Generation 65 Nanometer ... less than 1.250 Volts @ 1600 Mhz
2nd Generation 45 Nanometer ... less than 1.100 Volts @ 2000 Mhz

-> Core i

1st. Generation 45 Nanometer ... less than 1.000 Volts @ 1600 Mhz
2nd Generation 32 Nanometer ... less than 1.000 Volts @ 1600 MHz
3rd Generation 22 Nanometer ... less than 0.900 Volts @ 1600 MHz
4th Generation 22 Nanometer ... less than 0.800 Volts @ 800 MHz

Use Hardware Monitor to confirm that Power has decreased as follows:

-> Core i

2nd Generation 32 Nanometer ... less than 8 Watts
3rd Generation 22 Nanometer ... less than 4 Watts
4th Generation 22 Nanometer ... less than 2 Watts

Test:

Allow your rig to "settle" for 10 minutes, then measure Ambient temperature. Use Real Temp to measure your Core temperatures. Remember to correct your results to Standard Ambient. Power (watts) isn't monitored on Core 2 processors, but for general reference, idle power for several popular CPU's is shown above under Section 7 - Relative Temperatures.

Results:

At stock settings, Core i 2nd, 3rd and 4th Generation processors should idle at less than 8C above Ambient. This means that at 22C Standard Ambient your Cores should idle just under 30C. Certain Core 2 variants and Core i 1st Generation variants may idle a few degrees higher. The better your cooler and the lower your idle power, the lower your idle temperatures.


Section 13 - Improving Temperatures

Whether your computer is a stock workstation or an overclocked gaming rig, achieving the lowest possible temperatures always depends on components, configuration and air flow. Here's a few thoughts:

* Intel's cooler is barely adequate at stock. If you intend to overclock then upgrade your cooler.
* Good cable management yields good airflow. Use zip-ties, patience and attention to detail.
* Axial flow graphics cards recirculate heat. Linear flow cards exhaust heat from the case.

Examples:

Axial - http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Linear - http://www.newegg.com/Product/Product.aspx?Item=N82E168...

* Axial cards work well with a liquid cooled CPU. Linear cards work well with an air cooled CPU.
* A hot case stresses hard drives, memory, chipsets, voltage regulators and power supply.
* If your case doesn't breath well, then perhaps it's time to upgrade to one that does.
* High performance computers need unrestricted airflow in and out, so location is critical.
* Good fans are important, but if you want a quiet computer, then consider a fan controller.
* If your rig runs 24/7, then hard drive and fan bearings are wearing, and dust is accumulating.
* Clean the dust out of your rig. Perform regular Planned Maintenance Inspections (PM's).

Concerning Thermal Interface Material (TIM), here's some helpful links:

Thermal Paste Comparison, Part One: Applying Grease And More - http://www.tomshardware.com/reviews/thermal-paste-heat-...
Thermal Paste Comparison, Part Two: 39 Products Get Tested - http://www.tomshardware.com/reviews/thermal-paste-perfo...


Section 14 - Summary

* Standard Ambient temperature is 22C.
* Ambient affects all computer temperatures.
* As Ambient increases, thermal headroom decreases.
* Don't expect BIOS or CPU temperature to be accurate.
* Core temperatures respond instantly to changes in load.
* 80C sustained Core temperature is hot.
* Core temperatures in the mid 70's are safe.
* Excessive Vcore and temperatures accelerate electromigration.
* Prime95 Small FFT's is the standard for thermal testing.
* Deviations between individual Cores can be up to +/- 5C.
* Core temperature sensors are more accurate at high temperatures.
* Don't expect idle temperatures to be accurate.
* Sensors can be tested with Real Temp.
* No temperatures can be less than or equal to Ambient.

Section 15 - Intel Processor Temperature FAQ http://www.intel.com/support/processors/sb/CS-033342.ht...

_________________________________________________


Thank you for reading. I hope this Guide has answered your temperature questions.

CompuTronix :sol: