Just out of curiosity, could you explain to me the mechanics of electrical and heat conduction in chemicals? I have a general idea about electricity, but really none about heat.
That is more complicated then you know! But a quick, simplified description.
Heat is just a form of energy, more specifically (and simplified) the kinetic energy of the molecules).
Water has a high heat capacity because it is polar and forms very strong hydrogen bonds. This means it takes a lot of energy to make the bonds between each distinct water molecule to twist, vibrate and separate. This is what gives water is very high specific heat, hydrogen bonding (very important chemical concept). Hydrogen bonding is a form of intermolecular attraction, and there are many other types as well.
Like I said, that is a very simplified version, and I am not sure you will even understand that, as it requires you to know a lot of other stuff chemistry related.
As far as a substance to put over the contacts, it might be possible. It would have to be something that it’s self obviously does not conduct electricity, and is not soluble in water.
The first thing that comes to my mind would be a paraffin wax. It is an extremely good electrical insulator and not soluble in water. Depending on what kind you have the melting range is from ~47-65
oC (~116-150
oF). So you would have to get some with the upper range, and monitor the system carefully because if you hit the melting point then it will wash off in the water. It has a specific heat of about half that of water, so it should transfer heat fairly well.
It would be easy to melt then dip the components in, however it would be very hard to get a very thin layer. If the layer is thick it will just trap the heat in and have the wrong effect.
It however burns very readily and very hotly (it is used in some bipropellant rockets).
The biggest problem is though, that it might melt, as a CPU processor will have some very high heat spots and it so it might just be impossible to use it for this application or to get a thin enough layer
Your best and safest and cheapest bet would probably actually be to build an air tight chamber around the parts (make sure you have plenty of volume). Remove all the air from it, and fill the chamber up with Helium gas. Helium gas has a specific heat of over 5 times that of air, it has a higher specific heat then water actually. It is non reactive so it would not harm the components (and it is readily available and cheap). This would allow you to pull the heat away from the computer components really fast and efficiently. You would then need to remove the heat from the helium. You could pump the helium through a radiator to remove the heat.