Power for one server isn't just input watts!
Wednesday, April 28, 2010
1:26 PM
Power needs for one server aren't just input watts! 
The power needed to run one server 
= wattage for server + wattage for cooling
≈ wattage for server * (1 + 1/E) 
where E = efficiency of cooling << 100% 
In other words, the total power consumption for running a server is usually considerably more than double its average power consumption as a unit! 