SAN JOSE, Calif. – Intel Corp. announced positive results from a year-long test of a novel system that cools servers by immersing them in mineral oil. The CarnotJet vat from Green Revolution Cooling (Austin, Texas) delivered a cooling power usage effectiveness (PUE) rating of 1.02-1.03 without impacting performance of the seven dual-socket Xeon servers, Intel said.
The results suggest the oil vats require only two to three percent additional energy than the servers themselves. By contrast, a typical data center runs at a cooling PUE as high as 1.6, meaning the non-IT systems require 60 percent in additional energy beyond the power needed to run the servers.
Some companies such as Facebook have opened new data centers in areas where they can use ambient air to cool their systems, eliminating the costs of air conditioning. But they are not the targets for the oil-immersion systems.
“If you are going to add a significant amount of capacity and have systems with a lot of density and don’t have good air flow in your data center, this is worth looking at,” said Mike Patterson, a senior thermal architect for data centers at Intel who supervised the test.
The Texas Advanced Computing Center is one data center that fits that description. It has been testing the same technology for several years. But oil immersion is not for everyone.
“We probably have ten different advanced cooling technologies we are analyzing…each has its pros and cons, and each market has different priorities,” said Patterson.
Intel dunked seven Xeon servers for a year in a CarnoJet vat from Green Revolution Cooling.
The Intel group is working on a proposal to study immersion cooling with a two-phase fluid that boils off and condenses, transferring heat. “There are a number of other liquid cooling approaches including cold plates for CPUs to plates for full servers, so we are very much in our path-finding phase,” he said.
For its part, Intel has no further plans to use the oil-immersion approach, in part, because it has plenty of space in its data centers where air flow is good. However Patterson’s group is analyzing the trade-offs of building an “oil-optimized platform.” In today’s servers “the heat sinks and fan control built into the platforms are for air cooling,” he said.
Intel conducted the oil-immersion test after overcoming some of its own skepticism.
“We asked a lot of tough questions and they had pretty good answers for all of them so we put a pilot together,” said Patterson. “There’s almost an emotional reaction [against oil immersion] at first, so people say they would never do that, but when they see the potential [energy] savings, they see there’s something there,” he said.
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