I got the solution after years of this coil whine ******!
Its stand light go into settings SYTEM SETUP-LIGHT IN MOTION: Selects the brightness level of the light on the stand. The adjusting range is from Level 0 to 3 if you go to 0 or 3 coil whine stops!
And i dont even use original stand i got my monitor from day 1 on arm!
