Had a buddy with a micro-cray about 15 years ago. It was a little bit bigger than a standard desktop, it was filled with oil. Of course it was built that way, so all of the electrical connections were apparently sealed or soldered, it had it's own recirculating system. I never did take it apart though, too messy lol. You could possibly do the same thing with the r808's, but you will have to make sure that any connections are sealed or soldered. Just a secondary note, you'll still need a pump, radiator and fans since if you leave the oil in one place without cooling it will eventually exceed the temperature working limits of the chips.

Cheers