here they have submerged their rig in transformer oil as it is nonconductive. It works ok, but..... eeeeh, well the oil has a high vescosity, so its hard to pump, and it mixes bad, so you get hotspaot around your cpu or whatever. If there was a fluid of water like vescosity that was dilectric then it would be an awsome cooling setup.
btw, if you chillt he oil like they did the vescosity rises and it even gets worse.
OH! I remember an article where thye submerged the board in to flourent, ins nonconductive. haha , that one was funny, they used liquid nitrogen to cool it, they did it in steps as to not strees the physical hardware material, they dumped a bunch of dry ice in it, then started pumping the flourents through a spiral submerged in a tub of lq nitrogen, then they just started poaring the nitrogen in to the flourent i think, once the temps him -30 05 -50 the fluid in the capacitors froze, haha, and there went the board ^^