Power consumption is very important today, especially if you are running a room full of workstation/server systems. Adopting a series of more efficient machines could save a business thousands a year.
We used a calibrated meter to measure the power at the wall. No monitors were factored into the readings. All systems included the same graphics card, memory configuration and hard drive population.
We measured wattage at the socket when running Cinebench R11.5 64 bit which loads all cores to 100% utilisation. The graphics card was inactive during the reading.
The Intel Xeon E5 2660 system consumes up to 160 watts when loaded, which is a fantastic result, this drops to around 80-90W when idle.