Humming sound

[kilian tuning]

11820While solving my electrical problems (BLS and a short circuit which occurred while measuring bls connector for power... solved that...) i discovered where the humming sound comes from (very annoying sound, even audible inside the car), it comes from inside the ecu housing, its the highest black thing (relais?) shown on the pic below...i took it out and the sound was gone...
is it normal or need to be replaced (dont know what the function of it is either, its number 395...

http://i1229.photobucket.com/albums/ee469/mavada1/DSC06891.jpg

[Chung]

It could be related to this:

http://www.rs6.com/showthread.php/22817-Buzzing-from-ECU-area-with-ignition-on...