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But even that assumes all the IT load will be for servers. Certainly there will be power going to servers, network switches, etc., so the total would be lower than that. And if the NSA is using any larger servers (which considering its history, it most likely is), the number could be substantially lower than that. The average power consumption for a TOP10 supercomputer in 2008, for example, is about 1.3 megawatts, which in itself equals 2,600 500-watt servers.
Research is to see what everybody else has seen, and think what nobody else has thought.