do you feel the fan working or is it really turned off???
my NAS ex4 have allways the fan working (normaly is on the mininum RPM with 800 - 900 rpm
i dont know how ex2 works because i dont have one to compare but 0 rpm seems abnormal
EDIT :
WDTony have one ex2 and its the same like your so … it seems to be by design 
http://community.wd.com/t5/WD-My-Cloud-EX2/Unbiased-opinion-appreciated/td-p/703616
