Pentium Cooling System design

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Pentium Cooling System Design
By Jan Konecny Adam Retersdorf
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Pentium V Chip Cooling

• Quiet operation
• Reliable cooling
• Compact design
• Variable conditions

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Natural Vs Free convection

• Natural Convection

• Forced Convection

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Natural Vs Free convection

• Free Convection
• Very Quiet
• Low cost
• Efficient for low heat conditions
• Reliable

• Forced Convection
• Removes large quantities of heat
• Dependent on fan speed

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Preference of cooling Options

• Least expense Natural Convection no sink
• Natural Convection W/ Sink
• Forced Convection no Sink
• Most expense Forced Convection W/ Sink

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Experimental Setup

• Free and forced cases are housed inside the
  Plexiglas case
• Minimizes undesirable wind for Natural Convection
• Concentrates air velocity on chip for Forced
  Convection

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Experimental Setup

• Power source powered the fan and Chip Power
• K-Type Thermocouples
• Daq System (digital)
• Draft Reduced Laboratory

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Reasons of Apparatus Setup

• Easy to record Temperature data over a given
  amount of time
• Steady state could be obtained easier using this
  system rather than an open table
• Represents the Closed Case computer housing

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Measuring the Representations

• Ambient Temperature- simulates the air inside the
  case
• Chip Temperature- Lets us know the actual temp of
  chip(/-2.2C)
• Plexiglas Temperature- Represents the case
  temperature

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Measuring Heat Transfer
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Knowledge of Pin Q loss

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Heat transfer vs. Velocity Forced
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Heat transfer Vs. P in Natural
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Uncertainty analysis
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Resistance of Case-Air

• Rcase-air ((Tmod-Tamb)/ Qconv
• Rcase-air Vs. Pin (Natural Convection)
• Rcase-air Vs. Air Velocity (Forced Convection)

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R Vs. Pin Natural
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R Vs. Air Velocity Forced Convection
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First Order Approximation Analysis

• Forced Convection
• Determination of h value
• (from plot of h vs. air velocity)
• -Solving for chip temperature at different power
  levels and different air velocities

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Forced Convection
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Estimated Temperature Vs. Velocity
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Estimated Chip Temperature Vs. Power-in
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Natural Convection

• Determination of h value (Extrapolation of the
  data)
• Solving for chip temperature at different power
  levels

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Spacing Recommendations(Liquid Crystal Imaging
system)
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Recommendations

• Conservative approach
• 0 5W free convection with heat sink
• 5 15W forced convection without heat sink
• 15 30W forced convection with heat sink
• A Thermocouple controlled variable Speed fan
• Spacing air velocity recommendation
• (air velocities below 1.25m/s and above 3.5 m/s
  provide for less than 30mm thermal wake length)

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QUESTIONS

• ?