Processors
Desktop
Thermal Management for Intel® Core™2 Family Desktop Processors

This thermal guide covers thermal considerations for the boxed Intel® Core™2 Extreme processor, the boxed Intel® Core™2 Quad processor, and the boxed Intel® Core™2 Duo processor.1 The term "boxed Intel® processor" refers to processors packaged in a retail box for use by system integrators.

Systems using Intel® desktop processors all require thermal management. This document assumes the reader has a general knowledge of system operation, integration, and thermal management. Integrators who follow the recommendations presented here can provide their customers with more reliable systems and will see fewer customers returning with thermal management issues.

Thermal management in boxed Intel® desktop processor-based systems can affect both the performance (Thermal Monitor feature) and noise level (variable speed fan) of the system.

The Intel® Core™2 processor uses the Thermal Monitor feature to protect the processor during times when the silicon would otherwise operate above specification. More information on this feature as well as other thermal specifications can be found in the respective datasheet.

Intel® Core™2 Extreme Processor Datasheet
Intel® Core™2 Quad Processor Datasheet
Intel® Core™2 Duo Processor Datasheet

The Thermal Monitor feature is intended to help prevent long-term reliability damage to the processor and provide protection for unusual circumstances like higher than normal internal chassis temperatures or failure of a system thermal management component such as a system fan. In its active state, the Thermal Monitor feature scales back processor power consumption if the factory programmed thermal design temperature is exceeded. While the Thermal Monitor feature is active, the system's performance may drop below its normal peak performance level.

It is critical that systems be designed to maintain low enough internal chassis and processor inlet air temperatures to prevent the boxed Intel® desktop processor from entering a Thermal Monitor active state. In a properly designed system, the Thermal Monitor feature should never become active. It is recommended that the internal chassis temperature for boxed Intel® Core™2 Quad processor and boxed Intel® Core™2 Duo processor-based systems remain below the lower set point of the nominal operating environments, as shown in Table 1.

In addition to the Thermal Monitor feature, the boxed Intel® desktop processor fan heatsink uses a high quality variable speed fan. This allows the processor to remain within its operating thermal specifications by running at different speeds over a short range of internal chassis temperatures and processor power consumption levels.

As processor power has increased, required thermal solutions have generated more noise. Intel® has added an option to the boxed processor fan heatsink that allows system integrators to have a quieter system in the most common usage.

Previous generation boxed Intel® fan heatsinks contain built-in circuitry to control fan speed. They have a thermistor in the fan hub which measures the chassis ambient air temperature. The fan circuitry then adjusts the fan speed to properly cool the processor at the slowest speed allowable. If the chassis ambient temperature is cool, then the processor will run slower and quieter. If the ambient temperature is hot, then the fan will run faster.

This fan was designed to work in a variety of operating conditions so it had to be designed in such a way that it would cool the processor when running at its maximum power at any given ambient temperature as specified in Table 2. In normal operating environments, the processor rarely reaches its maximum power rating. Under most conditions the fan is spinning faster and louder than necessary. The fan heatsink is required to work this way so that it will properly cool the CPU in all specified operating environments.

Intel® has been aware of customer concerns over fan noise. In response, Intel® designed a fan speed control technology to take advantage of the fact that the processor is not always running at maximum power. This was done by basing the fan speed control on actual CPU temperature and power usage.

The speed of the fan heatsink is controlled by the additional 4th wire of the fan cable. This technology is sometimes referred to as “4-wire fan speed control.” The additional 4th wire sends a signal from the motherboard to the fan heatsink to control the speed. There is a thermal diode in the processor which measures actual CPU temperature. The processor sends information to the motherboard about its specific thermal requirements and the actual processor temperature. The motherboard then uses this information to optimally control the speed of the processor fan.

Figure 1 shows the current fan speed curve (red) of a 3-wire fan heatsink with thermistor-based fan speed control. The additional curves in blue represent fan operations at lower CPU temperature and power consumption levels based on the 4-wire fan speed control fan heatsink.

Note The boxed processor fan heatsink circuitry will not allow the fan to spin faster than necessary in order to meet worse case power usage at any given ambient temperature. The thermistor control is always active to limit maximum fan speed. (The Intel® Core 2 Extreme processor actually has the fan thermistor disabled to allow maximum user flexibility in overspeed environments. If the motherboard does not support 4-wire fan speed control, the fan will spin at full speed.)

The “Max Temp” in figure 1 represents the fan heatsink upper set point or worse case ambient temperature of 38°C. The “Min Temp” represents the lower set point or the slowest possible fan speed at an ambient temperature of 30°C. (Also see Table 1). These temperatures should not be confused with the fan inlet temperature which is different.

A 4-wire fan does not guarantee a quieter system. If the processor is being used in a hot environment and under heavy loads, the fan will have to run fast enough to properly cool the processor. The internal chassis temperature is required to be maintained at the temperature specified in Table 2. The acoustic benefits of the 4-wire based fan speed control may also vary depending on the specific motherboard implementation since the acoustical benefits are reliant on the particular motherboard implementation of fan speed control.

Intel® also developed a motherboard-based fan speed control starting with Intel® 965 chipset-based motherboards called Intel® Quiet System Technology (Intel® QST). This new technology uses a PID (Program Integral Derivative) controller that can measure the rate of change of the processor temperature, thus predicting when the processor will reach its maximum temperature. If implemented correctly by the motherboard manufacturer, the control algorithm will operate the processor fan at minimum speed under most operating conditions. Since Intel® QST can predict when the processor will reach its maximum temperature, it will delay increasing the fan speed until just the right moment in order to keep the processor from exceeding its maximum temperature. Consult with your motherboard manufacturer to see which motherboards they offer with support for Intel® QST.

Table 1. Boxed Processor Variable Fan Heatsink Set Points

For Boxed Intel® Core™2 Quad Processors and Boxed Intel® Core™2 Duo Processors in the 775-land package2
Internal Chassis Temperature (°C) Boxed Processor Fan Heatsink Set Points
X <= 301 Lower Set Point: Fan speed constant at lowest fan speed. Recommended temperature for nominal operating environment.
Y = 35 Recommended maximum internal chassis temperature for boxed Intel® Core 2 Duo processor-based systems.
Z >= 381 Higher Set Point: Fan speed constant at highest fan speed.
  1. Set point variance is approximately ±1°C from fan heatsink to fan heatsink.
  2. The boxed Intel® Core™2 Extreme processor has the fan thermistor disabled to allow maximum user flexibility in overspeed environments. Motherboard-based fan speed control is required to operate the fan at lower speeds.

Figure 1. Internal Chassis Temperature Impact On Noise

Allowing processors to operate at temperatures beyond their maximum specified operating temperature may shorten the life of the processor and can cause unreliable operation. Meeting the processor temperature specification is ultimately the responsibility of the system integrator. When building quality systems using the boxed Intel® processor, it is imperative to carefully consider the thermal management of the system and verify the system design with thermal testing. This document details specific thermal requirements for the boxed Intel® processors. System integrators using the boxed Intel® processors should become familiar with this document as well as the related document listed below.

Related document

The following document describes general thermal management techniques and proper integration of a boxed processor in order to improve system quality and reliability. It should be used in conjunction with the information on this page.

Chassis system airflow considerations

Thermal management

The ultimate goal of thermal management is to keep the processor at or below its maximum operating temperature. Proper thermal management depends on two major elements:

  1. A heatsink properly mounted to the processor
  2. Effective airflow through the system chassis.

Proper thermal management is achieved when heat is transferred from the processor to the system air, which is then vented out of the system. Boxed Intel® processors are shipped with a high-quality variable speed fan heatsink, which can effectively transfer processor heat to the system air. It is the responsibility of the system integrator to ensure each design has adequate system airflow.

Fan heatsink

The fan heatsink included with the boxed Intel® processor must be securely attached to the processor. Thermal interface material, preapplied at the factory and attached to the bottom of the heatsink, provides effective heat transfer from the processor to the fan heatsink. The fan cable provides power to the fan by connecting to a motherboard-mounted power header and also allows the transfer of information to and from the fan with the motherboard. Only motherboards with proper hardware monitoring circuitry can use the fan speed signal since additional circuitry is required for motherboard-based fan speed control.

The fan is responsible for providing a good local air stream. This air stream transfers heat from the heatsink to the air inside the system. However, moving heat from the processor to the system air is only half the task. Sufficient system airflow is also needed in order to exhaust the air. Without a steady stream of air through the system, the fan heatsink will re-circulate warm air, and therefore may not cool the processor adequately.

Thermal interface material replacement for fan heatsink

Thermal interface material is required for proper heat transfer from the processor to the fan heatsink. The boxed Intel® processor will have preapplied thermal interface material attached to the bottom of the heatsink. Intel® does not recommend the removal of the thermal interface material located on the bottom of the new boxed processor fan heatsink. Removal of this material may cause damage to the processor and will void the boxed processor warranty.

However, if you must remove and re-use the fan heatsink due to a processor reinstallation, it may require replacement depending on how long the fan heatsink has been attached and in use. A good guideline is this - when in doubt, remove the old thermal interface material and apply new thermal interface material.

Do not try to add additional thermal interface material or apply thermal interface material that is not directly supplied from Intel®. This part may be ordered online at the click.intel.com* pay-for-spares online store. You may also choose to contact Intel® Customer Support to receive replacement thermal interface material.

Chassis recommendations

Systems based on the boxed Intel® desktop processor must use a chassis that comply with the ATX specification (revision 2.2 or later) or microATX specification (revision 1.0 or later), depending on the motherboard form factor. Intel® recommends system integrators using ATX form factor motherboards to choose a chassis that complies with the ATX specification. Likewise, system integrators using microATX form factor motherboards should choose a chassis that complies with the microATX specification.

The chassis must also support a lower internal ambient temperature than many standard ATX and microATX desktop chassis designs. The internal chassis temperature for systems based on the boxed Intel® desktop processors should not exceed the values listed in Table 2 when the chassis is used in a maximum expected room temperature of 35°C. Most chassis designed for the boxed Intel® desktop processor use extra internal chassis fans to improve airflow and many include ducting to bring cool air directly to the processor fan heatsink. Optimum results are best achieved by using a Thermally Advantaged Chassis (TAC) version 1.1 or later.

Intel® recommends using a Thermally Advantaged Chassis from the Tested Chassis List to ensure proper chassis airflow, electrical support (ATX12V or SFX12V power supply), and compatibility with boxed Intel® processors. Chassis designs that pass this thermal testing provide system integrators with a starting place for determining which chassis to evaluate. It is strongly recommended that system integrators perform thermal testing on the chassis selected for each system configuration, even when using a chassis on the Tested Chassis List.

Intel® desktop processor thermal specifications

Table 2 lists the power dissipation of boxed desktop processors for various processors. You may also refer to the following documents for more details on processor power specifications:

Intel® Core™2 Extreme Processor Datasheet
Intel® Core™2 Quad Processor Datasheet
Intel® Core™2 Duo Processor Datasheet

A simple evaluation of the temperature of the air entering the fan heatsink can provide confidence in the system's thermal management. The best description for how to measure this is provided in the Thermal and Mechanical Design Guide in the section entitled "Thermal Metrology". Evaluation of test data makes it possible to determine if a system has sufficient thermal management for the boxed processor. Systems based on the Intel® boxed processors listed below should have a maximum expected fan inlet temperature of either 39°C or 40°C for the maximum expected external ambient temperature, which is typically calculated at 35°C.

Table 2. Boxed Intel® Processor Thermal Specifications

Processor
Number
Processor Core
Frequency
(GHz)
Maximum Case
Temperature
(°C)
Maximum
Recommended
Fan Inlet
Temperature

(°C)
Processor
Thermal
Design
Power
(W)
Notes

QX9775

3.20

63

39

150

1

QX9770

3.20

55.5

See datasheet

136

1

QX9650

3

64.5

39

130

1

QX6850

3

64.5

39

130

1

QX6800

2.93

64.5

See datasheet

130

1, 4

QX6800

2.93

64.5

39

130

1

QX6700

2.66

64.5

39

130

1

X6800

2.93

60.4

39

75

1

Q9650

3

71.4

39

95

2

Q9550

2,83

71.4

39

95

2

Q9550S

2.83

76.3

39

65

2

Q9450

2.66

71.4

39

95

2

Q9400

2.66

71.4

39

95

2

Q9400S

2.66

76.3

39

65

2

Q9300

2,50

71.4

39

95

2

Q8400

2.66

71.4

39

95

2

Q8400S

2.66

76.3

39

65

2

Q8300

2.50

71.4

39

95

2

Q8200

2.33

71.4

39

95

2

Q8200S

2.33

76.3

39

65

2

Q6700

2.66

71

39

95

2

Q6600

2.40

62.2

39

105

2,4

Q6600

2.40

71

39

95

2

E8600

3.33

72.4

40

65

3

E8500

3.16

72.4

40

65

3,5

E8500

3.16

72.4

40

65

3

E8400

3

72.4

40

65

3

E8300

2.83

72.4

40

65

3

E8200

2.66

72.4

40

65

3

E7600

3.06

74.1

40

65

3

E7500

2.93

74.1

40

65

3

E7400

2,80

74.1

40

65

3

E7300

2.66

74.1

40

65

3

E7200

2.53

74.1

40

65

3

E6850

3

72

40

65

3

E6750

2.66

72

40

65

3

E6700

2.66

60.1

40

65

3

E6600

2.40

60.1

40

65

3

E6550

2.33

72

40

65

3

E6420

2.13

60.1

40

65

3

E6400

2.13

61.4

40

65

3

E6320

1.86

60.1

40

65

3

E6300

1.86

61.4

40

65

3

E4700

2.60

73.3

40

65

3

E4600

2.40

73.3

40

65

3

E4500

2.20

61.4

40

65

3

E4400

2

61.4

40

65

3

E4300

1.80

61.4

40

65

3


Notes
  1. These specifications are from the Intel® Core™2 Extreme Processor Datasheet.
  2. These specifications are from the Intel® Core™2 Quad Processor Datasheet.
  3. These specifications are from the Intel® Core™2 Duo Processor Datasheet.
  4. This specification applies only to the B-step processor.
  5. This specification applies only to the C-step processor .

1Not all Intel® Boxed Processors include a fan heatsink solution in the package.

This applies to:

Intel® Core™2 Duo Desktop Processor
Intel® Core™2 Extreme Processor
Intel® Core™2 Quad Processor

Solution ID: CS-030615
Last Modified: 08-Oct-2010
Date Created: 05-Jul-2009
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