For immersion cooling any kind of electronics, it's hard to beat 3M Fluorinert. There is a fairly wide range of the chemically amd electrically inert fluid. I can't find the site right now, but I remember a guy in Austrailia immersing a rig in Fluorinert & floating dry ice in the fluid. Depending on the choice of fluid, it's quite possible. The viscocity of most of the Fluorinert family of fluids is as close to water as is possible. Some having pour points as low as -110°C.
The properties are perfect for my aplication but I don't have that kind of cash to throw at this experiment. That really is too bad. This fluid is the sh@*&@!...
here is a link. http://multimedia.mmm.com/mws/mediaw...ttt&TCdpTTTT6-
they sell the stuff by the pound and 3/4 gal is 11lbs... 1lbs =$20 unless you get it in 5gal incraments which is $18/lbs = $1320.