About paraffin: Its not a conductor of electricity. There are many types of parafine in market(thin or fat fluidity). So the conductivity, the ph and the viscosity, are affected from the fluidity of the original mixture. Melting point is 48 to 66 degrees of Celcium. Paraffin is a saturated hydrogoncarbon so it ''ll not react with the parts of the pc

Oils are pretty good insulators, however, so if you submerge your system in something like a mineral oil it would be like wrapping insulation around all of your parts.  In addition, because oils don't conduct electricity at all, if any gets into the contacts between the pieces of your system and your motherboard it can affect how they transmit a signal thus hurting your computer's ability to work.

i was going to make my pc completely, no upgrading etc, and then glue / silicon all the connections of parts, say ram, cpu, pci etc, to prevent oil from getting in there.

as oils being an insulator, are you saying you dont think that the oil will draw the heat out of the components (such as the cpu), i am aware that oil isnt as good as water (de-ionised for a pc), i still dont trust water very much and other tests have proven water to crash the pc (although no damage was caused), an example of an oil pc project is here  http://www.tomshardware.com/2006/01/09/strip_out_the_fans/page2.html
they used vege oil, but i feel it was a temporary task (as vege oil would go rancid after a period of time) plus, its all brown, clear would be sooo much cooler.

Wouldn't you have to compress the nitrogen though? Wouldn't the motherboard explode/implode under the pressure?

Jdurg answered your question. Oils are insulators. They don't conduct electricity at all. As far as conductivity at 30°C (I'm assuming C), I think with jdurg's post we can already rule out oil. My post was simply an example of what some people are doing/have done. I realize it's an expensive solution to your problem, but maybe your someone who would want to do that kind of thing.

As far as P-man's question goes, you would need to purchase one of those high powered special compressors for this to be a long term solution. As far as the mother board imploding/exploding it would not. At hospitals, atleast ones in my area, they have massive compressors that are used to produce liquid O2. You get lots of N2 and other gasses in the air obviously. Here is the thing though when you compress air (in general) to a high enough point it will liquefy. This is obviously an exothermic process and the heat has to be drawn off and dissipated. The liquified gas though can then be drawn from the compressor and distilled into what you want. You can then place it in normal air pressure and it will remain a liquid till it absorbs enough heat to go back into a gas.

Further reading:
http://en.wikipedia.org/wiki/Dry_Ice#Dry_Ice
http://en.wikipedia.org/wiki/Charles%27_law
(this link may just be helpful)