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Intel CPU Temperature Guide

Intel CPU Temperature Guide - by CompuTronix

Update: June 14th 2018


Preface

The topic of processor temperatures can be very confusing. The purpose of this Guide is to provide an understanding of standards, specifications, thermal relationships and test methods so temperatures can be uniformly tested and compared. This Guide supports Core i, Core 2, Pentium and Celeron Desktop processors running Windows Operating Systems.


Contents

Part 1: How It Works

Section 1 - Introduction
Section 2 - Ambient Temperature
Section 3 - CPU Temperature
Section 4 - Core Temperature
Section 5 - Package Temperature
Section 6 - Throttle Temperature

Part 2: Sorting It Out

Section 7 - Specifications And Temperature
Section 8 - Overclocking And Voltage
Section 9 - The TIM Problem

Part 3: Tests And Methods

Section 10 - Thermal Test Tools
Section 11 - Thermal Test Basics
Section 12 - Thermal Test 100% Workload
Section 13 - Thermal Test Idle

Part 4: Tips And Conclusions

Section 14 - Improving Temperatures
Section 15 - Summary
Section 16 - References


Part 1: How It Works


Section 1 - Introduction

Intel Desktop processors have temperatures for each "Core" and a temperature for the entire "CPU". Core temperatures are measured at the heat sources near the transistor "Junctions" inside each Core where temperatures are highest. CPU temperature is instead a single measurement centered on the external surface of the CPU's "Case" or "Integrated Heat Spreader" where the cooler is seated.

Core temperature is considerably higher than CPU temperature due to differences in the proximity of sensors to heat sources.

http://imgur.com/jkFil5t.jpgIntel Desktop processors have two Thermal Specifications. For Core temperature it's "Tjunction" which is also called "Tj Max" (Temperature Junction Maximum) or “Throttle” temperature. For CPU temperature it's "Tcase" (Temperature Case) which is a factory only measurement.

Tcase and Tjunction (Tj Max) Thermal Specifications are both shown in Intel’s Datasheets which include specifications, definitions and technical descriptions. However, Intel's Product Specifications website is a quick reference that shows Tjunction (Tj Max) for 7th and 8th Generation processors or Tcase for 6th Generation and earlier processors.

Here's where temperatures get confusing:

When users of 6th Generation and earlier processors look up their Thermal Specification at Intel's Product Specifications website, most don't realize what Tcase actually means. Since there are numerous software utilities for monitoring Core temperature, they assume it must be Core temperature.

Tcase is not Core temperature.

Intel has no documentation which describes the relationship between specifications and temperature in a practical sense, so explanations are given in Section 7.

In order to get a clear perspective of processor temperatures, it's important to become familiar with the terminology and specifications.

Use CPU-Z to identify your processor:

• CPU-Z - http://www.cpuid.com/softwares/cpu-z.html

http://imgur.com/6sDkflm.jpgYou can then look it up at Intel's Product Specifications website:

• Intel Product Specifications - http://ark.intel.com/#@Processors

https://imgur.com/rhNeyDe.jpgFor more detailed information, links to Intel’s Datasheets are shown in Section 16 - References.

When asking temperature questions on Forums, you should provide the following information:

CPU
Cooler
Core speed
Core voltage at load
Load test software
Temperature software
Load & idle Core temperatures
Memory
Motherboard
Graphics Card
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 22°C or 72°F, which is normal room temperature. Ambient temperature is a reference value for Intel’s Thermal Specifications. Knowing your Ambient temperature is important because all computer temperatures increase and decrease with Ambient temperature. Use a trusted analog, digital or infrared (IR) thermometer to measure Ambient temperature.

Here's the temperature conversions and a short scale:

http://imgur.com/7TX6Bvm.jpgWhen 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.

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


Section 3 - CPU Temperature

Also called "Tcase" (Temperature Case), this is a factory only temperature measured on the external surface of the Integrated Heat Spreader (IHS). Tcase isn't tested on retail processors, but for lab testing only, engineering samples are used. A groove is cut into the surface of the IHS where a "thermocouple" sensor is embedded at the center. The processor is installed, the stock cooler is seated, the thermocouple is connected to measurement devices and the temperature is then tested under carefully controlled conditions.

http://imgur.com/nikTkvD.jpgFor retail processors, one of two different methods are used to display “CPU” temperature in BIOS and in monitoring utilities.

Previous Method: Core 2 Socket 775 and Core i 1st Generation Socket 1366 processors have a single Analog Thermal Diode centered under the Cores to substitute for a laboratory thermocouple. The Analog value is converted to Digital (A to D) by the motherboard's Super I/O (Input / Output) chip, then is calibrated to look-up tables coded into BIOS. The monitoring utility provided by the motherboard manufacturer on your Driver CD displays “CPU” temperature in Windows. ”CPU” temperature is typically inaccurate and can vary greatly with BIOS updates.

Present Method: Core i Sockets 115x and Core X Socket 20xx processors don't have an Analog Thermal Diode, but instead substitute the "hottest Core" for "CPU" temperature, which is a confusing contradiction in terms. This is the temperature shown in BIOS, and on some recent motherboards is shown on the two digit "debug" display. The monitoring utility provided by the motherboard manufacturer on your Driver DVD displays “CPU” temperature in Windows, but is actually the "hottest Core".

Regardless of the Method used, CPU temperature in BIOS is higher than in Windows at idle, because BIOS boots the processor without power saving features and at higher Core voltages to ensure that it will initialize under any conditions.

Note: The term “CPU” temperature is commonly used as a general term for any processor temperatures.


Section 4 - Core Temperature

Also called "Tjunction" (Temperature Junction), this is the temperature measured at the heat sources near the transistor “Junctions” inside each Core by individual Digital Thermal Sensors (DTS).

http://imgur.com/dvgqRlK.jpgSince the Digital Thermal Sensors (DTS) are located where temperatures are highest, and Tcase is measured on the Integrated Heat Spreader (IHS) where temperatures are lower, there's a temperature difference between DTS and IHS locations. At 100% workload, the difference is about 5°C on Core 2 and Core i processors through 2nd Generation, but the difference on 3rd through 8th Generation can be up to 25°C. For details see Section 9 - The TIM Problem.

Core temperature is the standard for thermal measurement.

Intel's specification for DTS accuracy is +/- 5°C. Although sensors are factory calibrated, deviations between the highest and lowest Cores can be up to 10°C. Sensors are more accurate at high temperatures to protect against thermal damage, but due to calibration issues such as linearity, slope and range, idle temperatures may not be very accurate.

Core temperatures increase and decrease instantly with changes in load.

Intel’s specification for DTS response time is 256 milliseconds, or about 1/4th of a second. Since Windows has dozens of Processes and Services running in the background, it’s normal to see rapid and random Core temperature “spikes” or fluctuations, especially during the first few minutes after startup, which should eventually settle. Any software activity will show some percentage of CPU Utilization in Task Manager, where unnecessary Tray items, Startups, Processes and Services that contribute to excessive or continued spiking can be disabled. For details see Section 13, Note 1.

Here's the operating range for Core temperature:

Core temperatures above 85°C are not recommended.

Core temperatures below 80°C are ideal.

http://imgur.com/Svr2si8.jpgCore temperatures increase and decrease with Ambient temperature.

Idle temperatures below 25°C are generally due to Ambient temperatures below 22°C.

High Core temperatures occur during stress tests, rendering or transcoding, but are lower during less processor intensive workloads such as applications and gaming. Core temperatures can vary greatly among gaming titles due to differences between CPU and GPU workloads.

Here’s a list of variables that affect Core temperature:

Ambient temperature
CPU Cooler
Fan / Pump speed
Thermal Interface Material
IHS / Cooler flatness
Core count
Core speed
Core voltage
BIOS updates
Turbo Boost
Hyperthreading
Instruction Sets
Memory
Case design
Cable management
Computer location
Ventilation
GPU cooler type
SLI / CrossFire
Dust

For more information see Section 14 - Improving Temperatures.


Section 5 - Package Temperature

Package temperature is the hottest sensor, which is typically the hottest Core.

Package temperature is shown in a few software utilities such as Hardware Info - https://www.hwinfo.com/download.php - Package temperature can be affected by Intel's on-Die Integrated Graphics Processor Unit (IGPU).


Section 6 - Throttle Temperature

Also called "Tj Max" (Temperature Junction Maximum), this is the Thermal Specification that defines the Core temperature limit at which the processor will Throttle (reduce Core speed and voltage) to protect against thermal damage. Throttle temperatures are shown below for several popular processors, including Thermal Design Power (TDP) and idle Power, which are expressed in Watts (W).

Core

8th Generation 14 nanometer i7 8700K / i5 8600K (TDP 95W / Idle 2W),
7th Generation 14 nanometer i7 7700K / i5 7600K (TDP 91W / Idle 2W),
6th Generation 14 nanometer i7 6700K / i5 6600K (TDP 91W / Idle 2W):
Tj Max (Throttle temperature) = 100°C

5th Generation 14 nanometer i7 5775C / i5 5675C (TDP 65W / Idle 2W):
Tj Max (Throttle temperature) = 96°C

4th Generation 22 nanometer i7 4790K / i5 4690K (TDP 88W / Idle 2W),
4th Generation 22 nanometer i7 4770K / i5 4670K (TDP 84W / Idle 2W):
Tj Max (Throttle temperature) = 100°C

Legacy Core

3rd Generation 22 nanometer i7 3770K / i5 3570K (TDP 77W / Idle 4W):
Tj Max (Throttle temperature) = 105°C

2nd Generation 32 nanometer i7 2600K / i5 2500K (TDP 95W / Idle 4W):
Tj Max (Throttle temperature) = 98°C

1st Generation 45 nanometer i7 860 / i5 750 (TDP 95W / Idle 12W),
1st Generation 45 nanometer i7 920 D0 (TDP 130W / Idle 12W):
Tj Max (Throttle temperature) = 100°C

Core 2 45 nanometer Q9550 E0 (TDP 95W / Idle 16W),
Core 2 65 nanometer Q6600 G0 (TDP 95W / Idle 24W):
Tj Max (Throttle temperature) = 100°C


Part 2:


Section 7 - Specifications And Temperature

The previous Sections explained Intel’s specifications regarding how temperatures are measured. This Section focuses on how Thermal Design Power (TDP) relates to Thermal Specifications, and why Tcase and Tj Max are inconsistent with sensible real-world Core temperatures.

TDP specifications are expressed in Watts, which is Power that's dissipated as heat. The key word in “Thermal Design Power” is Design. Major variables include Microarchitecture, Core count, Core speed, Core voltage, Hyperthreading and Instruction Sets. Problems with high Core temperatures are most prevalent among processors with more than 2 Cores, higher TDP, higher Core speeds and Hyperthreading such as i9’s and i7’s, especially when overclocked.

i5’s follow i7 Designs, while Pentiums and Celerons follow i3 Designs. Processors with Hyperthreading run hotter at the same TDP than those without, and processors with AVX Instruction Sets run hotter when executing AVX code than those without. This means at 100% workload, i9's, i7’s and i3’s may reach TDP, while i5’s, Pentiums and Celerons typically won’t. However, most overclocked processors will exceed TDP, which requires better cooling.

Tcase specifications are factory only IHS temperatures, which users can't measure. Tcase values vary with processor TDP and stock cooler TDP. Coolers and CPU’s of different TDP values are often packaged together. Several Generations of Quad Core CPU's at 77, 84, 88 and 95 Watts were packaged with a universal 95 Watt cooler (E97378). But for 6th, 7th and 8th Generation 91 and 95 Watt processors, Intel's 130 Watt stock cooler is sold separately (BXTS15A).

Intel Stock Coolers - http://www.anandtech.com/show/10500/stock-cooler-roundup-intel-amd-vs-evo-212/3

Compared below are three Intel processor / cooler combinations with respect to TDP and Tcase Specifications:

Example 1: i7 2600K 95 Watts TDP / Cooler 95 Watts TDP / Difference Watts / Tcase 72°C.
Example 2: i7 3770K 77 Watts TDP / Cooler 95 Watts TDP / Difference 18 Watts / Tcase 67°C.
Example 3: i7 6700K 91 Watts TDP / Cooler 130 Watts TDP / Difference 39 Watts / Tcase 64°C.

The higher the cooler TDP is from the processor TDP, the lower the Tcase specification. Likewise, when the stock cooler is replaced with a higher TDP aftermarket cooler, temperatures are lower. Tcase varies with different TDP coolers and CPU's. In the examples above, the Tcase values imply that the 6700K is less thermally capable than the 2600K, which is very misleading, since the 6700K has a higher Throttle temperature, as shown above in Section 6.

The Datasheets show both Tcase and Tjunction (Tj Max) Thermal Specifications for Desktop processors. The Product Specifications website shows Tcase for 6th Generation and earlier, or Tjunction (Tj Max) for 7th Generation and later, yet the 6700K and 7700K have exactly the same Thermal Specifications. Mobile (laptop) processors don’t have an Integrated Heat Spreader, so they don’t have Tcase specifications; only Tjunction (Tj Max).

Intel’s move away from Tcase on their website synchronizes Desktop and Mobile Thermal Specifications. From Core 2 processors in 2006 to today’s Core i processors, Tj Max has always been the limiting Thermal Specification; not Tcase. Although useful for developers of cooling solutions, Tcase is IHS temperature; not Core temperature. Since Core temperature is considerably higher than IHS temperature, which users can't measure, Tcase is an irrelevant specification.

Tj Max specifications are shown in the Datasheets below in Section 16 - References, and in the monitoring utility "Core Temp" - http://www.alcpu.com/CoreTemp

http://imgur.com/CiSMl7P.jpgTj Max specifications also vary with TDP specifications. The highest Tj Max Throttle temperature is 105°C (221°F). Although most processors Throttle at 100°C (212°F), lower TDP variants may Throttle at lower Core temperatures. Nevertheless, it’s not advisable to run your CPU near it's thermal limit, just as common sense tells you not to run a vehicle with the temperature gauge pegged in the red "hot" zone.

If your hottest Core is near it's specified Tj Max Throttle temperature, then your CPU is already too hot. The consensus among well informed and highly experienced system builders, overclockers and reviewers, is that cooler is better for ultimate stability, performance and longevity. Experts all agree that it's prudent to observe a reasonable thermal margin below Tj Max. So regardless of environmental conditions, hardware configurations, workloads or any other variables, Core temperatures above 85°C are not recommended.


Section 8 - Overclocking And Voltage

Overclocking is always limited by two factors; voltage and temperature. No two processors are identical; each processor is unique in voltage tolerance, thermal behavior and overclocking potential, which is often referred to as the "silicon lottery" or luck of the draw. As Core speed (MHz) is increased, Core voltage (Vcore) must also be increased to maintain stability. This increases Power consumption (Watts) which increases Core temperatures. Overclocked processors at higher Vcore might run up to 50% above TDP, so high TDP air or liquid cooling is crucial.

Overclocking should not be attempted with Vcore settings in “Auto” because BIOS will apply significantly more voltage than is necessary to maintain stability. We know that excessive heat over time damages electronics, so even when using manual Vcore settings, excessive Vcore and Core temperature may result in accelerated "Electromigration" - https://www.google.com/?gws_rd=ssl#q=Electromigration

This prematurely erodes the traces and junctions within the processor's layers and nano-circuits, which will eventually result in blue-screen crashes that become increasingly frequent over time. As a rule, CPU's become more susceptible to Electromigration with each Die-shrink. However, the exception is Intel's 14 nanometer Microarchitecture, where advances in FinFET technology have improved voltage tolerance.

Here’s a list of maximum recommended Vcore settings:

Core

8th Generation 14 nanometer ... 1.400 Vcore
7th Generation 14 nanometer ... 1.400 Vcore
6th Generation 14 nanometer ... 1.400 Vcore
5th Generation 14 nanometer ... 1.400 Vcore
4th Generation 22 nanometer ... 1.300 Vcore

Legacy Core

3rd Generation 22 nanometer .... 1.300 Vcore
2nd Generation 32 nanometer ... 1.375 Vcore
1st Generation 45 nanometer .... 1.400 Vcore

Core 2 45 nanometer ... 1.400 Vcore
Core 2 65 nanometer ... 1.500 Vcore

When tweaking your processor near it's highest overclock, keep in mind that for an increase of 100 MHz, a corresponding increase of about 50 millivolts (0.050) is needed to maintain stability. If 70 millivolts (0.070) or more is needed for the next stable 100 MHz increase, it means your processor is overclocked beyond it's capability.

With high TDP air or liquid cooling you might reach the Vcore limit before 85°C. With low-end cooling you’ll reach 85°C before the Vcore limit. Regardless, whichever limit you reach first is where you should stop. Testing is explained in Sections 10 through 13.

Remember to keep overclocking in perspective. For example, the difference between 4.5 GHz and 4.6 Ghz is less than 2.3%, which has no noticeable impact on overall system performance. It simply isn’t worth pushing your processor beyond recommended Core voltage and Core temperature limits just to squeeze out another 100 MHz.


Section 9 - The TIM Problem

Core i 3rd Generation and later processors are very sensitive to small increases in voltage and frequency, and are more difficult to cool than 2nd Generation and earlier processors, so cooling is crucial. Here's why:

(1) 3rd Generation and later processors are "small Die", which have significantly less surface area in contact with the Integrated Heat Spreader (IHS), than "large Die" 2nd Generation and earlier processors.

(2) 3rd Generation and later processors have more transistors densely packed into their small Die than large Die 2nd Generation and earlier processors.

(3) 3rd Generation and later mainstream processors use Thermal Interface Material (TIM) between the Die and IHS, which has relatively poor thermal conductivity. "Indium" solder, which has good thermal conductivity, was instead used in 2nd Generation and earlier processors.

http://imgur.com/JFRvS1c.jpgSince the material that seals the perimeter of the IHS to the Substrate is slightly too thick, this tends to create space between the Die and IHS, which can also cause the TIM to compress unevenly. The effect is high Core temperatures, with some processors showing wide deviations between Cores, or one Core which runs much hotter than it's neighbors.

This has encouraged some overclockers to "delid" or remove their processor's IHS and replace Intel's TIM with liquid metal TIM, allowing thermal conductivity much closer to Indium solder. Typical results are dramatically lower Core temperatures with less deviation between Cores.

Beware that delidding will void your warranty, and if not performed carefully, can damage or destroy your processor.

Rather than delid with the risky razor blade method, you can safely delid with a "delidding tool" such as the Rockit 88 - https://rockitcool.myshopify.com/

Silicon Lottery - https://siliconlottery.com/collections/all/products/delid - is a company that tests, bins and sells overclocked, delidded "K" CPU's. They also offer professional delidding services, and give the following figures on how much Core temperatures at 100% workload are improved by delidding:

8th Generation ... Coffee Lake - 12° to 25°C
7th Generation ... Kaby Lake - 12° to 25°C
6th Generation ... Skylake - 7°C to 20°C
5th Generation ... Broadwell - 8°C to 18°C
4th Generation ... Devil's Canyon - 7°C to 15°C
4th Generation ... Haswell - 10°C to 25°C
3rd Generation ... Ivy Bridge - 10°C to 25°C

To illustrate the scope of this problem, thermal characteristics among soldered and TIM’d processors are compared below:

http://imgur.com/nIPUrfr.jpgCore temperatures on earlier processors with Indium solder between the Die and IHS are consistently within 5°C above IHS temperature, which indicates good thermal conductivity. However, Core temperatures on later Generations with TIM between the Die and IHS vary up to 25°C above IHS temperature, which indicates relatively poor thermal conductivity and uniformity.

Note: Intel uses engineering samples with soldered Integrated Heat Spreaders for testing and developing specifications.


Part 3:


Section 10 - Thermal Test Tools

In order to properly test your Core temperatures, you'll need:

• A trusted analog, digital or infrared (IR) thermometer to measure Ambient temperature.

You'll also need the following Freeware utilities downloaded and installed:

• Core Temp - http://www.alcpu.com/CoreTemp
• CPU-Z - http://www.cpuid.com/softwares/cpu-z.html
• Prime95 v26.6 - http://www.mersenneforum.org/showthread.php?t=15504

• Optional; Install SpeedFan if you’d like to use the “Charts” to see your thermal signatures - http://www.almico.com/sfdownload.php
• Optional; Install Hardware Info if you'd like to see advanced monitoring details - https://www.hwinfo.com/download.php
• Optional; Install Real Temp (developed for Intel processors) to test your Digital Thermal Sensors - http://www.techpowerup.com/downloads/2089/real-temp-3-70

Note: Sensing thermal performance by touch is like feeling a campfire from 20 meters. Since hundreds of millions of nanometer scale transistors are densely packed into a tiny Die, heat dissipates throughout the Package over a relatively large area and thermal gradient to the cooling surface, about 3 millimeters from the heat source. (3 millimeters = 3,000,000 nanometers).

http://imgur.com/OGElpsh.jpgEven at 100% workload nothing will feel hot; exhaust airflow, cooling fins, heat pipes or water blocks will feel warm, and liquid cooling tubes will have a moderate temperature differential.


Section 11 - Thermal Test Basics

When working with processor temperatures, taking a methodical approach is always recommended. One of the guiding principles for properly conducting a test, is that it's crucial to set up the same conditions and follow the same procedures every time. This minimizes variables so results will be consistent and repeatable.

Here's some reasons why users find processor temperatures so confusing:

Terminology and specifications
Abundance of misinformation
Inconsistent test procedures

Since Ambient temperature, hardware configurations and stress test software are major variables, in order to compare apples to apples it's important to be specific. “Load” or “full load” are misleading user terms that could mean anything. Gaming, applications, rendering, transcoding and streaming are partial, fluctuating workloads with fluctuating temperatures, which aren’t well suited for testing thermal performance.

Not all loads are created equal. “Stress” tests can be characterized into two categories; stability tests which are fluctuating workloads, and thermal tests which are steady workloads. Intel tests their processors at a steady 100% TDP workload to validate Thermal Specifications.

Prime95 version 26.6 Small FFT's is ideal for CPU thermal testing, because it's a steady 100% workload with steady Core temperatures that typically runs Core i variants with Hyperthreading and Core 2 processors within +/- a few % of TDP. No other utility so closely replicates Intel's test conditions. This is the utility Real Temp uses for testing Core temperature sensors.

http://imgur.com/4hHdAwn.jpgUtilities that don't overload or underload your processor will give you a valid thermal baseline. Here’s a comparison of utilities grouped as thermal and stability tests according to % of TDP, averaged across six processor Generations at stock settings rounded to the nearest 5%:

http://imgur.com/VwY8pG5.jpgHigher TDP tests produce higher Core temperatures. All tests will show 100% CPU Utilization in Windows Task Manager, which indicates processor resource activity, not % TDP workload. Although actual Power dissipation (Watts) varies with Core Speed, Core voltage and workload, Prime95 v26.6 Small FFT’s always provides a steady 100% workload, whether you’re running stock or overlocked.

Note: 2nd through 8th Generation i3, i5 and i7 CPU's have AVX (Advanced Vector Extension) Instruction Sets. Prime95 versions later than 26.6 run AVX code on the CPU's Floating Point Unit (FPU) which causes unrealistic temperatures up to 20°C higher due to excessively high TDP workloads, as shown above. Other high TDP utilities have similar results.

AVX can be disabled in Prime95 versions later than 26.6 by inserting "CpuSupportsAVX=0" into the "local.txt" file in Prime95's folder. However, since Core temperatures will be the same as 26.6, it's easier to just use 26.6. AVX doesn't affect Core i 1st Generation, Core 2, Pentium or Celeron processors since they don't have AVX Instruction Sets.

If you’re overclocked and run AVX apps such as for rendering or transcoding, you may need to reduce Vcore and Core speed or upgrade your cooler and case fans so Core temperatures don’t reach 85°C. Many 6th, 7th and 8th Generation motherboards address the AVX problem by providing offset adjustments in BIOS. An offset of -2 (200 MHz) is usually sufficient.

Asus RealBench does not require an AVX offset, but runs a realistic AVX workload typically within +/- a few % of TDP, and is an excellent utility for testing overall system stability, whether you're running stock or overclocked. This is the utility Silicon Lottery uses for testing CPU stability.

• Asus RealBench - http://rog.asus.com/rog-pro/realbench-v2-leaderboard/

Under proper test conditions, there are only three relevant values:

Ambient temperature
Core temperatures at steady 100% workload
Core temperatures at dead idle

Sections 12 and 13 will explain how to properly test your rig using standardized methods which minimize hardware, software and environmental variables. Follow the "Setup" in both Sections to replicate Intel's test conditions. Each 10 minute test will establish a valid thermal "baseline" at steady 100% workload and at dead idle.


Section 12 - Thermal Test 100% Workload

Note 1: Keep in mind that we're thermal testing only. Stability testing is not within the scope of this Guide, which assumes your rig is properly assembled, configured and stable. If you're overclocked, then a combination of stress tests, apps or games must be run to verify CPU stability.

Prime95's default test, Blend, is a fluctuating workload for testing memory stability, and Large FFT's combines CPU and memory tests. As such, Blend and Large FFT's both have fluctuating workloads which aren’t well suited for CPU thermal testing.

Other stability tests such as OCCT have cycles that exceed 120% workload, which again aren’t well suited for CPU thermal testing. However, OCCT will by default, terminate the CPU tests at 85°C.

The "Charts" in SpeedFan span 13 minutes, and show how each test creates distinct thermal signatures.

http://imgur.com/AV0iCxD.jpgShown above from left to right: Small FFT's, Blend, Linpack and IntelBurn Test.

Note the steady thermal signature of Small FFT's, which allows accurate measurements of Core temperatures. A steady 100% workload is key for thermal testing so the CPU, cooler, socket, motherboard and voltage regulators can thermally stabilize.

http://imgur.com/zyvJ9LZ.jpgShown above from left to right: Small FFT's, Intel Extreme Tuning Utility CPU Test, and AIDA64 CPU Test.

Intel Extreme Tuning Utility is also a fluctuating workload. Although AIDA64's CPU test is a steady workload, it's far below TDP, which is insufficient for thermal testing. All other AIDA64 CPU test combinations are fluctuating workloads, which again aren't well suited for thermal testing.

Setup:

The objective of this test is to determine your rig's maximum cooling capability at 100% workload. This allows Core temperatures to be tested under ideal conditions, which will later reveal how variables such as case covers and fan speeds affect temperatures under normal use.

Testing should be performed with your computer clear of desk enclosures or items that block airflow. Intel tests their processors on an open bench, without a case, so covers should be removed and all fans and circulating pump (if equipped with liquid cooling) at 100% RPM.

Core temperatures increase and decrease with Ambient temperature.

Testing near 22°C Standard Ambient is preferred so as to provide normal thermal headroom. During warmer months if adequate A/C isn’t available, then test late at night or early in the morning when Ambient is lowest. If you can’t test near 22°C, then you can "normalize" your results to establish a valid thermal "baseline". This minimizes variables so results will be consistent and repeatable.

Summer room temperatures are usually above 22°C, which also decreases overclocking headroom. If your Ambient is 5°C above normal, then subtract 5°C from your Core temperatures to normalize your test results. So if Core temperature is 80°C, then normalized Core temperature is 75°C.

Winter room temperatures are usually below 22°C, which also increases overclocking headroom. If your Ambient is 5°C below normal, then add 5°C to your Core temperatures to normalize your test results. So if Core temperature is 70°C, then normalized Core temperature is 75°C.

Although the relationship between Core temperature and Ambient temperature isn't precisely 1:1, Core temperatures normalized to 22°C should be close to Core temperatures actually tested at 22°C. Establishing baseline Core temperatures is important because as Ambient changes, if you maintain your hardware configuration and BIOS settings, a baseline gives you a consistent point of reference. You can repeat the test whenever you like to see if your rig is maintaining thermal performance.

Test:

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

Results:

Here’s how an adequately cooled rig should perform, while allowing for higher Ambient temperatures:

http://imgur.com/VkRfAMZ.jpgIf Core temperatures reach 85°C, you should improve cooling and / or reduce Vcore and Core speed, regardless of Ambient temperature. High Core temperatures may also occur during rendering or transcoding, but are lower during less processor intensive workloads such as applications and gaming. Intel’s specification for Digital Thermal Sensor (DTS) accuracy is +/- 5°C. This means deviations between the highest and lowest Cores can be up to 10°C. On processors that use Turbo Boost or have an uneven application of TIM, deviations might exceed 10°C by a few degrees.

http://imgur.com/kc6xu5x.jpgAverage 75°C
Highest 77°C
Lowest 73°C
Deviation 4°C

On processors with more than 2 Cores, the inner Cores typically run warmer because they’re insulated by the outer Cores. 2nd through 4th Generation processors are more affected due to the location of the Integrated Graphics Processor Unit (IGPU). Core temperatures are more evenly balanced on 5th through 8th Generation processors due improvements in physical layout.

Note 2: When viewing your temperatures in Core Temp, values that reach 81°C or higher will change from black to amber, which indicates caution. Simultaneously running two or more monitoring utilities could cause them to interfere with one another.

Normalize your results to Standard Ambient and record the values for future reference.


Section 13 - Thermal Test Idle

Look closely at the SpeedFan Charts above, where idle temperatures are shown between load temperatures. Note that some Cores have more "range" than others and idle lower. Sensors can be tested with Real Temp. Core temperature sensors are more accurate at high temperatures for Throttle protection, but due to calibration issues such as linearity, slope and range, idle temperatures may not be very accurate.

If "SpeedStep", also called Enhanced Intel SpeedStep Technology (EIST), is disabled in BIOS, then depending on Vcore and Core speed, idle Power can be nearly 30 Watts, which will result in high idle temperatures, especially when combined with high Ambient temperature.

Note 1: 6th Generation processors introduced "Speed Shift" technology in Windows 10, which responds much faster to changes in workload than "SpeedStep" due to having many more Core speed and Core voltage transition levels.

http://imgur.com/oAd9T4z.jpgSince 7th and 8th Generation Speed Shift is twice as fast as 6th Generation, some users complain of Core temperature spikes which can also cause fluctuations in fan RPM at idle. Motherboard manufacturers are developing BIOS fixes that include separate SpeedStep and Speed Shift settings with more flexible fan curves and time delay options.

Setup:

The objective of this test is to determine your rig's maximum cooling capability at dead idle. This allows Core temperatures to be tested under ideal conditions, which will later reveal how variables such as case covers and fan speeds affect temperatures under normal use.

In addition to using the previous Setup in Section 12, SpeedStep and all "C" States must be enabled to achieve the lowest possible idle temperatures. Also, if Windows Power Options for "Balanced" or "Power saver" is not set correctly, then SpeedStep will not work ... OR ... if Windows Power Options is set to "High performance", then SpeedStep will not work because Minimum processor state can‘t be set.

To check this, go to Control Panel > Power Options > Change plan setting > Change advanced power settings > Processor power management > Minimum processor state. The default setting is 5%. If it's not, then correct it and click Apply.

http://imgur.com/kwD8fen.jpgRestart into BIOS and confirm that you've saved your settings to a Profile. Next, change all settings to stock (Default / Auto) including Vcore. Check that SpeedStep and all C States are still enabled, 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 just 1 or 2% CPU Utilization under the "Performance" tab in Windows Task Manager.

http://imgur.com/9i9v2dm.jpgUse CPU-Z to confirm that Core Voltage and Core Speed has decreased as follows:

Core

8th Generation 14 nanometer ... about 0.7 Volts @ 800 MHz <--
7th Generation 14 nanometer ... about 0.7 Volts @ 800 MHz
6th Generation 14 nanometer ... about 0.8 Volts @ 800 MHz
5th Generation 14 nanometer ... about 0.8 Volts @ 800 MHz
4th Generation 22 nanometer ... about 0.8 Volts @ 800 MHz

Legacy Core

3rd Generation 22 nanometer ... about 0.9 Volts @ 1600 MHz
2nd Generation 32 nanometer ... about 1.0 Volts @ 1600 MHz
1st Generation 45 nanometer ... about 1.0 Volts @ 1600 MHz

Core 2 45 nanometer ... about 1.1 Volts @ 2000 MHz
Core 2 65 nanometer ... about 1.25 Volts @ 1600 MHz

http://i.imgur.com/5uZtBb5.jpgUse Core Temp to confirm that Power has decreased as follows:

Core

8th Generation 14 nanometer ... about 2 Watts <--
7th Generation 14 nanometer ... about 2 Watts
6th Generation 14 nanometer ... about 2 Watts
5th Generation 14 nanometer ... about 2 Watts
4th Generation 22 nanometer ... about 2 Watts

Legacy Core

3rd Generation 22 nanometer ... about 4 Watts
2nd Generation 32 nanometer ... about 4 Watts
1st Generation 45 nanometer ... about 12 Watts (Socket 1156)

http://imgur.com/PctHpzH.jpgNote 2: Fluctuations are normal and expected. Power (Watts) isn't measured on 1st Generation Socket 1366 variants and Core 2 processors. Power is lower on processors with 2 Cores and higher on those with more Cores. Idle Volts and Watts may differ depending on motherboard and BIOS. For general reference, idle Power for several popular processors is shown in Section 6.

Test:

Allow your rig to "settle" for 10 minutes, then use your thermometer to measure Ambient. Use Core Temp to measure your Core temperatures.

Results:

2nd through 8th Generation processors should idle less than 10°C above Ambient. Certain 1st Generation variants and most Core 2 processors may idle several degrees higher. Many 45 nanometer Core 2 variants have sensors that "stick" in the 40's showing false high idle temperatures, and some 6th Generation variants show false low idle temperatures below Ambient. Idle temperatures may not be very accurate. Better cooling and lower idle Power yields lower idle temperatures.

Normalize your results to Standard Ambient and record the values for future reference. When finished testing, restore your system to it's previous configuration.


Part 4:


Section 14 - Improving Temperatures

Whether your computer is an overclocked gaming rig, a stock workstation or an all-purpose family PC, achieving the lowest possible temperatures always depends on components, configuration and airflow. Here's a few tips:

• Intel coolers are barely adequate at stock. If you want to overclock then upgrade your cooler.
• BIOS updates sometimes include Vcore optimizations, which can drop Core temperatures.
• Don't use Auto Vcore settings. Auto applies excess voltage which increases Power and heat.
• Disabling Hyperthreading is an option which will significantly decrease Core temperatures.
• Disabling Multi Core Enhancement (MCE) will also help to decrease Core temperatures.
• Disabling Turbo Boost is another option which will further decrease Core temperatures.
• Decreasing Maximum processor state in Power Options will decrease Core temperatures.
• Memory overclock or XMP Profiles can cause Core i CPU's to run several degrees hotter.
• Axial flow graphics cards recirculate heat. Linear flow cards exhaust heat from your case.

Examples:

Axial - http://www.newegg.com/Product/Product.aspx?Item=N82E16814487248
Linear - https://www.newegg.com/Product/Product.aspx?Item=9SIA85V5RB1062

• SLI / CrossFire works best with Linear cards. Axial cards dump excessive heat in your case.
• A hot case stresses SSD’s, HDD’s, memory, chipsets, voltage regulators and power supply.
• High performance computers need unrestricted airflow in and out, so location is critical.
• If load temperatures drop over a few °C with case covers removed, it means poor airflow.
• Good cable management creates good airflow. Use zip-ties, patience and attention to detail.
• Quality fans are important, but if you want a quiet computer then consider a fan controller.
• If your CPU is too hot, you may need to adjust fan curves in BIOS or your software utility.
• If your case just doesn't breathe well, then perhaps it's time to upgrade to one that does.
• If your rig runs 24/7, then dust is accumulating and moving parts are wearing prematurely.
• Clean the dust out of your rig. Perform regular Planned Maintenance Inspections (PM's).
• Replace your TIM. Some Thermal Interface Materials may begin to fail after 2 to 3 years.
• If IHS / cooler surfaces aren't perfectly flat, "lapping" can drop load temperatures a few °C.
• Delidding will significantly drop Core temperatures on 3rd through 8th Generation CPU’s.

Thermal Interface Material (TIM):

Note 1: Delidding requires that you use only liquid metal TIM between the Die and IHS. Typical silicon TIM will fail in a relatively brief period of time. A process known as “pump-out” will cause silicon TIM to ooze out from between the Die and IHS due to thermal cycling. A highly recommended liquid metal TIM is Thermal Grizzly Conductonaut - http://www.thermal-grizzly.com/en/products/26-conductonaut-en

Here’s a short list in order of thermal conductivity:

Indium - 81.8 W/mk (Used in earlier processors with soldered IHS)

Liquid Metal TIM (IHS to Die)

Thermal Grizzly Conductonaut - 73.0 W/mk
CoolLaboratory Liquid Ultra - 38.4 W/mk
CoolLaboratory Liquid Pro - 32.6 W/mk

Typical Silicon TIM (IHS to Cooler)

Thermal Grizzly Kryonaut - 12.5 W/mk
Arctic Silver 5 - 9.0 W/mk
Arctic Cooling MX4 - 8.5 W/mk

Thermal Paste Comparison, Part One: Applying Grease And More - http://www.tomshardware.com/reviews/thermal-paste-heat-sink-heat-spreader,3600.html

Thermal Paste Comparison, Part Two: 39 Products Get Tested - http://www.tomshardware.com/reviews/thermal-paste-performance-benchmark,3616.html

Installing Intel's stock cooler - https://www.youtube.com/watch?v=5qczGR4KMnY

Choosing an aftermarket cooler:

Air Cooling vs Water Cooling: Things You Need To Know - http://www.tomshardware.com/forum/id-2196038/air-cooling-water-cooling-things.html

Note 2: Liquid coolers, whether high-end custom loops or All-In-One (AIO), sometimes called Closed Loop Coolers (CLC), will eventually fail. It’s not a question of if; it’s a question of when. Pumps have moving parts that wear out, so those which run 24/7/365 are prone to premature failure. AIO units are notorious for failures due to inferior pump quality, whereas custom loops typically use high-end pumps which have greater longevity.

Air coolers, especially high-end units with dual or "push-pull" fans, tend to be extremely reliable as fan failures are infrequent. However, Intel stock coolers, as well as several aftermarket low-end units with push-pin fasteners are notorious for temperature problems due to push-pins pulling loose from the motherboard. Coolers with push-pins should be avoided in favor of coolers which use proper fastening hardware with a back-plate.

Alternatives to the Hyper 212+/Evo for budget cooling - http://www.tomshardware.com/forum/id-2705157/alternatives-hyper-212-evo-budget-cooling.html


Section 15 - Summary

• Standard Ambient temperature is 22°C or 72°F.
• Ambient affects all computer temperatures.
• No temperatures can be less than or equal to Ambient.
• As Ambient increases, thermal headroom decreases.
• BIOS or CPU temperature may not be very accurate.
• Tcase is IHS temperature; not Core temperature.
• Core temperature is the standard for thermal measurement.
• Core temperatures respond instantly to changes in load.
• Tj Max is the thermal limit; not Tcase.
• Tcase is an irrelevant Thermal Specification.
Core temperatures above 85°C are not recommended.
• Core temperatures below 80°C are ideal.
• Package temperature is the hottest sensor.
• Excessive Vcore and temperatures accelerate Electromigration.
• Prime95 v26.6 Small FFT's is ideal for thermal testing.
• Deviations between highest and lowest Cores may be 10°C.
• Core temperature sensors are more accurate at high temperatures.
• Idle temperatures may not be very accurate.
• Sensors can be tested with Real Temp.


Section 16 - References

- 1) Intel® Processor Temperature FAQ - http://www.intel.com/support/processors/sb/CS-033342.htm

- 2) Intel® Product Specifications - http://ark.intel.com/#@Processors

- 3) Intel® Core™ Processors Technical Resources - http://www.intel.com/content/www/us/en/processors/core/core-technical-resources.html

- 4) 8th Generation Intel® Processor Datasheet for S-Platforms, Volume 1 - https://www.intel.com/content/www/us/en/processors/core/8th-gen-processor-family-s-platform-datasheet-vol-1.html

- 5) 7th Generation Intel® Core™ X-Series Processor Family ™ i7-7800X, i7-7820X, and i9-7900X Datasheet, Volume 1 - https://www.intel.com/content/www/us/en/products/processors/core/6th-gen-x-series-datasheet-vol-1.html

- 6) 7th Generation Intel® Core™ X-Series Processor Family ™ i5-7640X and i7-7740X Datasheet, Volume 1 - https://www.intel.com/content/www/us/en/products/processors/core/7th-gen-x-series-datasheet-vol-1.html

- 7) 7th Generation Intel® Processor Datasheet for S-Platforms, Volume 1 - http://www.intel.com/content/www/us/en/processors/core/7th-gen-core-family-desktop-s-processor-lines-datasheet-vol-1.html

- 8) Intel® Core™ i7 Processor Family 6xx0 for LGA2011-v3 Socket Datasheet, Volume 1 - http://www.intel.com/content/www/us/en/processors/core/core-i7-6xxx-lga2011-v3-datasheet-vol-1.html

- 9) 6th Generation Intel® Processor Datasheet for S-Platforms, Volume 1 - http://www.intel.com/content/dam/www/public/us/en/documents/datasheets/desktop-6th-gen-core-family-datasheet-vol-1.pdf

- 10) The Truth about CPU Soldering - http://overclocking.guide/the-truth-about-cpu-soldering/

- 11) Desktop 5th Generation Intel® Core™ Processor Family Datasheet, Volume 1 - https://www.intel.com/content/www/us/en/processors/core/5th-gen-core-family-datasheet-vol-1.html

- 12) Intel® Core™ i7 Processor Family 5xx0 for LGA2011-3 Socket, Thermal Specifications - https://www.intel.com/content/www/us/en/processors/core/core-i7-lga2011-3-tmsdg.html

- 13) Intel Discusses i7 4790K Core Temperatures and Overclocking - https://www.youtube.com/watch?v=BGTnJkuqlbo

- 14) Desktop 4th Generation Intel® Core™ Processor Family, Datasheet, Volume 1 - https://www.intel.com/content/www/us/en/processors/core/4th-gen-core-family-desktop-vol-1-datasheet.html

- 15) Intel® Core™ i7 Processor Families 3xx0, 4xx0 for LGA2011-0 Socket Thermal Specifications - https://www.intel.com/content/dam/www/public/us/en/documents/design-guides/core-i7-lga-2011-guide.pdf

- 16) Desktop 3rd Generation Intel® Core™ Processor Family, Desktop, Thermal Specifications - https://www.intel.com/content/dam/www/public/us/en/documents/design-guides/3rd-gen-core-lga1155-socket-guide.pdf

- 17) i7-3770K vs. i7-2600K: Temperature, Voltage, GHz and Power-Consumption Analysis - https://forums.anandtech.com/threads/i7-3770k-vs-i7-2600k-temperature-voltage-ghz-and-power-consumption-analysis.2281195

- 18) 2nd Generation Intel® Core™ Processor Family Desktop, Thermal Specifications - https://www.intel.com/content/dam/www/public/us/en/documents/guides/2nd-gen-core-lga1155-socket-guide.pdf

- 19) Measuring Processor Power: TDP - https://www.intel.com/content/dam/doc/white-paper/resources-xeon-measuring-processor-power-paper.pdf

- 20) Intel® Core™ i5-600/i3-500 Desktop Processor, Thermal Specifications - https://www.intel.com/content/dam/www/public/us/en/documents/design-guides/core-i5-600-i3-500-pentium-6000-desktop-lga1156-tmdg.pdf

- 21) CPU Monitoring With DTS/PECI - http://www.intel.com/content/www/us/en/embedded/testing-and-validation/cpu-monitoring-dts-peci-paper.html

- 22) Intel® Core™ i7-800 and i5-700 Desktop Processor Series Thermal Specifications - https://www.intel.com/content/www/us/en/intelligent-systems/piketon/core-i7-800-i5-700-desktop-lga1156-thermal-guide.html

- 23) Intel® Core™ i7-900 Desktop Processor Extreme Edition Series and Intel® Core™ i7-900 Desktop Processor Series Datasheet, Volume 1 - http://www.intel.com/content/www/us/en/processors/core/core-i7-900-ee-and-desktop-processor-series-datasheet-vol-1.html

- 24) Intel® Core™2 Extreme Processor QX9000 Series, Intel® Core™2 Quad Processor Q9000, Q9000S, Q8000, and Q8000S Series Datasheet - http://www.intel.com/content/dam/www/public/us/en/documents/datasheets/core2-qx9000-q9000-q8000-datasheet.pdf

- 25) Intel® Core™2 Extreme Quad-Core Processor QX6000 Sequence and Intel® Core™2 Quad Processor Q6000 Sequence Datasheet - http://static.highspeedbackbone.net/pdf/31559205.pdf

- 26) Temperature measurement in the Intel® Core™ Duo Processor - http://arxiv.org/ftp/arxiv/papers/0709/0709.1861.pdf

___________________________________________________________________


I hope this Guide has answered your questions, and has provided you with a clear perspective of Intel processor temperatures.

Thank you for reading.

CompuTronix :sol:


About the Guide

The Intel CPU Temperature Guide is the result of more than 6,000 hours of ongoing research and hands-on testing spanning over 11 years. It is frequently updated as new information becomes available.

Published: 2007 - Core 2 Duo Temperature Guide, 2007 - Core 2 Quad and Duo Temperature Guide, 2009 - Core i and Core 2 Temperature Guide, 2013 - Intel CPU Temperature Guide.


About the Author

Based in Charlotte, North Carolina, USA. Interests include computers, electronics, technology, sailing and flying.

Experience: Building, overclocking, upgrading and troubleshooting PC’s since 1994.
Background: Medical Imaging Electronics - MRI Engineer. Aviation Electronics - US Navy Aircraft.
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