CPU Cooling

1
CPU Cooling

• Benjamin Crummett

2
Objective

• Reduce CPU operating temperature.
• Over clock the CPU without over heating it.

3
Starting Conditions

• Stock heat sink and fan.
• CPU operating temperature 45C.
• Ambient air temperature in computer case 28C.

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Increasing Air Flow

• 20 CFM 50 CFM

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Analytical

• T8 28C
• Afan .0049m2
• Afin .0028m2
• N 66
• L .04m
• ReL VL/n
• Nu hL/k .664 ReL1/2 Pr1/3
• q NhAfin (Ts T8)

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New Fan Results

• Original temperature 45C.
• Measured
• CPU temperature 39C.
• Calculated
• CPU temperature 38.8C.

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Over Clocking Results

• Increasing CPU speed from 2 GHz to 2.4 GHz
  increased CPU temperature from 39C to 45C.
• The new fan allowed the CPU speed to be increased
  20 without increasing the temperature from its
  original state.

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Conclusions

• Increasing air flow velocity increases convective
  heat transfer rate.

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Questions?