Very PC is developing oil-cooled servers to save energy costs. This small, UK-based PC builder is proposing to develop servers with their innards submerged in oil. A refrigerator cools the oil which keeps the servers nicely chilled; a neat response to the hot topic of global warming through excess energy use.

Very PC - a pun on very politically correct - produces green computers, such as the GreenPC 478 which needs less power than a 60 watt lightbulb. In a New Scientist article, Very PC MD Peter Hopton said: "It is possible to cut power consumption in half. You don't need to drive inefficient fans, or the usual air conditioning." The extra cost of buying the oil baths, piping and refrigerator is more than covered, he says, by savings on energy costs over the life time of the oil-cooled servers.

Unlike water immersion, oil does not affect the workings of the servers and is a better conductor of heat than fan-blown air. Hopton says his company tested putting a server rack into an oil bath with a refrigeration unit positioned to create convection currents to draw heat away from the electronics. "Using oil we could chill down to -20ºC, but between 0ºC and 10ºC looks to be best," he said. It needs less energy than chilling to -20ºC.

Hopton also says cooler servers develop fewer faults and can be packed closer together in racks. Fixing failed servers might take longer though - all the oil would have to be removed first from extracted server blades or rack shelves.

Cray used a special inert fluid from 3M, Fluorinert, to cool its Cray 2 supercomputer. That idea did not spread, though 3M still sells it. Oil is cheap and readily available.

The need for oil-cooling might be mitigated by having more power-efficient servers in the first place. Very PC plans to begin selling oil-cooled servers early in 2008.