CPU Cooling products which operate below the ambient room
temperature (some Peltier and Thermo-electric coolers for example)
should not use silicon-based materials because condensation may
occur and accelerate compound separation.
All "white" style TIM's exhibit compound breakdown over time due
to their thin viscosity and ceramic base (usually beryllium oxide,
aluminium nitride and oxide, zinc oxide, and silicon
dioxide). These interface materials should not be used from older
"stale" stock without first mixing the material very well.
Thicker carbon and metal-based TIM's may benefit from several
thermal cycles to establish a "cure" period which allows expanding
and contracting surfaces to smooth out any inconsistencies and
further level the material.
Under perfect conditions the
contact surfaces between the processor and cooler would be perfectly
flat and not contain any microscopic pits, which would allow direct
contact without the need for Thermal Interface Material.
But since we don't have perfectly flat surfaces, Thermal Material
must fill the tiny imperfections.
The greater the contact pressure between elements, the better
the contact conductance which will allow the thermal transfer of
heat energy to occur.
Generally speaking, you do not want an excessive amount of
pressure onto the processor as damage may result.
...science teaches us that a smooth flat mating surface
is the most ideal for CPU coolers.
It is critically important to remove the presence of air from
between the surfaces, and that using only enough Thermal Interface
Material to fill-in the rough surface pits is going to provide the
best results. In a perfect environment, your processor
would mate together with the cooler and compress metal on metal with
no thermal paste at all; but we don't live in perfect world
and current manufacturing technology cannot provide for this ideal
environment.
Silver is the best heat conductor on the periodic table of
elements. Copper is #2, Gold is #3, Aluminum #4, Iron is #25. Copper
is also 1.7 times more conductive than Aluminum.
OCZ Freeze is slightly better than Arctic Silver 5 as a thermal
paste.
Keep in mind that thermal paste is only meant to fill the gaps,
not coat the surface; perfectly flat metal on metal with no
material in-between is your ultimate goal.
...a single round drop of thermal paste roughly
half the size of a BB is more than sufficient to cover the entire
mating surface of a stock Intel-included cooler.
2 parallel lines of TIM running perpendicular to
the grains on the surface(s) spaced apart at 1/3 processor width is
ideal for square heatsinks.
