Power consumption (operation) 6.1 watts
Power consumption (idle) 3.6 watts
Power consumption (standby) 0.9 watts
Power consumption (sleep) 0.9 watts
WORK: 8,35 Watt => 4,16 Watt = ca. 50% MORE
IDLE: 4,16 Watt => 3,6Watt => ca. 13,5% MORE
PRO HDD mind you.
I guess you have more than one hard drive???
EDIT: Western Digital Red Pro SATA III 18TB (WD181KFGX)