Hey Everybody … i want to give you an Update about the Coil Whine sound.
After the support contacted me and sent me an new backplate for the HDD Drives. Today i recieved it and instantly installed it.
i can confirm after pushing the button that the coil Whine is completly gone … not a single suspicious sound out of the cube … so thank you for the great support and im happy that we found a solution for the problem more people might can have. 
Thanks !!!