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Index
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Index
The Chemistry of Cooling a PC
Computer Processors (CPUs)
generate heat
Transistors are semiconductors contained within
the CPU core
Moore’s Law dictates that
transistor count in CPUS
will double every couple of
years.
Resistance creates Heat
Generally Speaking:
More transistors = More Heat
Slide 1: The Chemistry of Cooling a PC
Heat creates “Electromigration” which destroys
sensitive circuits.
Heatsinks are used to
dissipate the heat from
computer CPUs
Performance has changed
dramatically over the years
Slide 2: The Chemistry of Cooling a PC
Heatsink design has gone from simple passive aluminium to actively cooled
copper or aluminium/copper hybrid.
• Heat Conduction of Copper = 380J s-1 m-1 K-1
• Heat Conduction of Aluminium = 200J s-1 m-1 K-1
Why?
• Specific Heat Capacity of Copper = 0.902J g-1 K-1
• Specific Heat Capacity of Aluminium = 0.385J g-1 K-1
However, Aluminium is 1/3rd of the weight so
Per unit volume, Copper can absorb more heat.
But: Aluminium looses heat faster then Copper.
= Good Hybrid Heatsinks.
Slide 3: The Chemistry of Cooling a PC
Water cooling: From Enthusiast to Mainstream

Why?
• Specific Heat Capacity of Water = 4.179J g-1 K-1
• Specific Heat Capacity of Air (1atm) = 1.01J g-1 K-1
Greater cooling potential, less noise, less stress on the system.
Slide 4: Water cooling: From Enthusiast to Mainstream
Problems with water systems:
• Water and Electricity = Bad
• >1 metal systems creates an electrochemical cell = erosion of
water blocks.
• All Copper systems are now primarily used.
However, problems with the water system now occur.
Slide 5: Water cooling: From Enthusiast to Mainstream
Many argue the water system should use distilled or
deionised water.
Deionised water
• Advantages: Removal of reactive ions.
• Disadvantages: Still solvated solids remain
Distilled Water (Boiled Water)
• Advantages: Pure water – nothing else solvated
• Disadvantages: A “void” in the water causes ions
from the Copper blocks to restore
ionic equilibrium
Slide 6: Water cooling: From Enthusiast to Mainstream
What can
be done
about it?
Possibly use a Copper solution in distilled water
• Common Ion Effect inhibits further ionisation.
Possible solutions:
• Copper Hydroxide
• Copper Nitrate
• Copper Carbonate
• Copper Oxide
Problems
• Lower heat capacity.
• Possible crystal growth if flow is slow.
• Chemically “active” Copper solutions.
• How soluble are they?
Slide 7: Water cooling: From Enthusiast to Mainstream
What can
be done
about it?
Use a completely different liquid like PFC’s
(Per-fluoro-carbons)
C6F14 : Bpt: 56ºC
• Non toxic, non corrosive, non electrically conducting.
Problems with PFCs
• Lower heat capacity
• If the pump fails – PFC boils
• Expensive and possible restricted use.
Slide 8: Water cooling: From Enthusiast to Mainstream
Summary
Type summary in here
Slide 9: Summary
Acknowledgments
• University of Alaska Physics Dept.
• University of Indiana Northwest
• CSL Metallurgical and Materials Engineering
Department
• Bit Technologies
• Wizard Designs
• Pro Cooling
Thank you for your attention!
Slide 10: Acknowledgments