Thermal Interface Materials 101: Class is in session…
In a perfect world, the ideal way to dissipate heat from the CPU to the
heatsink would be to have perfect smooth and flat contact between the two
surfaces. I mean smoother than a baby’s butt with not even as much as a single
molecule of air between them.
To have a perfectly smooth and flat surface
in this situation here means better than a mirror finish or a finish that’s
flatter than what we can provide with the normal lapping methods that PC
enthusiasts currently use. Even with the best “homegrown” lapping efforts we
still have microscopic voids that require a medium to fill them. Air is the
worst possible thermal interface so something has to be used to replace the air
that once filled that area.
You could have your heatsink machined or
ground perfectly flat, but then you have to ensure that the processor or
graphics chip is also flat to give you better contact. Since this is not really
a practical or realistic solution we have to determine just how far your
specific situation deviates from that ideal.
This is where a thermal
interface material such as thermal compound comes into the picture. It’s safe
to assume that the surface of a CPU or a heatsink is never going to be perfectly
flat in real world situations. As an illustration, imagine that you’ve place a
heatsink directly on contact area of a CPU. In that situation there will be
tiny gaps between the two that will not be visible to the naked eye unless
you’re Superman of course. The air in those voids conducts heat terribly and
has a very negative effect on the heat dissipation process. Therefore, a
conductive interface material with a thermal conductivity rating similar to the
mating surfaces is needed to fill these gaps to advocate positive heat
dissipation.
In overclocking situations
it’s especially imperative that you to use a good interface material because
your CPU is creating up to 75% more than the normal amounts of heat in those
situations.
More is not better! There
is a common misconception that you should slap a huge glob of thermal compound
between your CPU and heatsink. This simply is not true! This will be more of a
hindrance than help because even the best thermal compound is less conductive
than a perfect metal-to-metal contact area.
Next page: Applying this stuff
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