Oil-cooled servers could possibly be used by companies to lower their data center costs. A year-long test by Intel and Green Revolution Cooling saw that by submerging a rack of servers into a non-conducting mineral oil, it had the best Power Usage Effectiveness that Intel had ever seen using that metric, although it could still be improved.
The test saw two identical racks of server, one using standard data center cooling techniques, the other placed into a tack filled with 250 gallons of dielectric fluid. The oil temperature is kept low through the use of a pump with a heat exchanger. Although the findings were seen to be in favor of oil cooling over air, a thermal architect at Intel believes that by optimizing the server's heatsinks, temperature transfers could be improved and allow the servers to push for a higher clock speed.
As current data center design requires servers to have raised floors, air conditioning units, and other kinds of building infrastructure, an oil-based version would require less of the construction, potentially saving companies on both start-up construction and ongoing power costs.
As for the future viability of the system, Intel published research in 2008, showing that it is possible for servers to perform well when using air from outside the center to cool everything down. This "free-air cooling" has since been taken onboard by data center operators, including Apple for their North Carolina build.
