I came across a relevant post on immersion cooling (very informative):

Two Phase Open Bath Immersion Cooling Thread (https://bitcointalk.org/index.php?topic=313087.0)

Some interesting points from that post:

• Open bath immersion cooling makes the tank easier and cheaper to construct and the system is never pressurized at dangerous pressures.
• 3M has conducted experiments cooling 4KW heat loads using 1L of working fluid so in theory heat densities approaching 4,000 W/L are possible.
• For two phase immersion cooling we are interested in fluids which boil below the temperature limits of ASICs.
• It is not possible with two phase cooling to have temperatures less than the boiling point of the working fluid.
• The cost depends on supplier and volume being purchased but generally runs $80 to $100 per Liter.