GIGABYTE at CES 2017 demo'd a 2U server with an 8GPU, 2CPU system with 24 memory modules fully immersed in a bath of a 3M Novec hydrocarbon (an inert, non-conductive fluid). Covering the CPU/GPUs was nothing more than large copper heatsinks.
"The concept for this design is a two-phase change from liquid to vapor and back, using no pumps but relying on the fact that the gas will condense and fall back into the solution and sink, causing automatic cycling. To cool the vapor as it rises through the system, a cold radiator is placed inside the sealed system.
Novec 72DA liquid is a solution of 70% 1,2-trans-dichloroethylene, 4-16% ethyl nonafluorobutyl ether, 4-6% ethyl nonafluoroisobutyl ether and trace other similar methyl variants. The liquid has a boiling point of 45ºC at very low viscosity (0.4 cP, compared to 0.89 cP for water), but also a low specific heat capacity (1.33 J/g/K, compared to 4.184 for water). "
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