Uneven Surfaces
A microscope will show you that neither the surface of a heat spreader nor the surface of a heat sink are really smooth. What looks even to the bare eye is full of pits and grooves.

When you press both surfaces together, only parts of the metal touch each other. Without a thermal compound, air fills the gaps. But air is a bad heat conductor. It's more of an insulator, actually. Thus, without thermal paste, much of the engineering that goes into heat spreaders and CPU coolers is wasted, as heat is only conducted where the metal surfaces touch.

Heat-Conducting Materials to the Rescue! Pastes and Pads
Clearly, the insulating air needs to be displaced by some thermal compound. Obviously, any thermal paste, pad, or liquid metal will conduct heat less effectively than the two metal surfaces involved. So, you want the application to be thin enough to not impose a lot of thermal resistance, but thick enough to overcome the surface imperfections of the heat spreader and sink.

- Everything You Wanted To Know About Cooling A CPU
- Interaction Of The Heat Spreader And Heat Sink
- The Differences Between AMD And Intel Heat Spreaders
- Choosing The Right Paste: More Than A Matter Of Price
- Applying Thermal Paste, Part One
- Applying Thermal Paste, Part Two
- Why Do We Test Each Paste In Four Scenarios?
- Get Ready For The Thermal Compound Benchmarks!
can't wait for part 2 - this was a great read!
Just curious. I have some 8/9/12 volt regulators that would eliminate the guessing games for resistor fan adapters(voltage depends on the fans current draw).
I have seen unregulated 6 volt power supplies range from 8-over 12 volts at low loads.
For a rather low price you can use a regulator to get whatever voltage you want
ohh yeah and...
I can't wait for the next part of this to be release
I also enjoyed using the IC Diamond thermal paste as it proved to cool very well but since it has a diamond based substance it can scuff the heat spreader.
My temps are quite good - really the choice of cooler is much much more important than the choice of paste.
Tell this to OEM's ever seen a hp, dell, Lenovo, Asus, Acer cpu after you take off the heatsink with thermal paste on it? it's oozed all over he place...
When delidding and applying Liquid Pro between the IHS and die, I "painted" a very thin layer. It was very difficult until the surface tension broke, then it was easy from there.
Otherwise, great article, can't wait to see the results.
I know you're glad to be nearing the end as that was a lot of time invested to completion.
Congratulations sir, on one of the best reviews I've seen come from Toms yet!
Ryan