I came across some crazy youtube videos - submerging the whole PC (motherboard, processor, memory, PSU, graphic card and even the SSD, except the HDD /CD/DVDROM ) into a custom built aquarium filled with mineral oil !!
 
The goods
- mineral oil absorb heat better than air
- it's non conductive so electronics can function inside
 
Wondering
- will the PC be more quiet ? (but the oil still needs cooling outside..)
- what will happen to the motherboard battery ? or capacitors ?
- super overclocking ?
- will the PC last longer inside mineral oil ???
 
Having so much fun today watching these videos - but no way I'm even thinking of trying it out ! LOL

Interesting......I haven't seen the videos yet, but wonder how well the fans would work under oil?
 

kinda risky without purpose- generated heat has to be dealt with one way or another; a cooler liquid will remove heat more effectively than air due to the density of molecules in contact with the heated material, but then that liquid will have to lose that heat/energy or the ambient temperature will rise. it is exactly the same principal as a normal air cooled system in a sealed room- the room will become hotter unless ventilated. laws of thermodynamics remain unchanged regardless of the medium 

Years ago, Ham radio operators used oil filled dummy load units to test transmitters, but that was discontinued when the EPA outlawed the PCB Oil.  Oil filled capacitors were used until the EPA outlawed the PCB oil.  Same way utility company power transformers used oil.  They were all replaced.  The oil filled capacitors that were in our (industrial) UPS system were replaced with non oil filled types. 
 
Even if its not PCB oil, I would still avoid that.

Submerged in mineral oil for cooling?  That's ridiculous.  Using quality fans will do the job just as efficiently without the mess.
 
Now if your goal is to have your motherboard as smooth as a baby's bottom, then yeah, mineral oil is every pediatrician's number one choice.

Regarding fan operation, it spins slower and some says it last longer.
 
Most builders admit it's not practical but just because they can. Longest system seems to run for 5 years (source : linus tech tips, youtube)

Wow, I haven't heard that one before...some things are really nice oiled up but I never pictured a computer as one of them.

This has been around since the socket A, 775 days.  It's more trivial than practical.  I would think the point of using oil is to not use fans.

Electronics submerged in "mineral oil" or "distilled water" make for interesting exhibitions... but I wouldn't recommend it for daily use.

kitekrazy1
This has been around since the socket A, 775 days.  It's more trivial than practical.  I would think the point of using oil is to not use fans.

It's even older than that, predating PCs altogether. Seymour Cray was doing it in the late 60's.