820-00291 iMac Chime Repeat.

[Mac Repairs]

Hi,

This is 2015 27 inch iMac.
Chime repeat.
Tried with new bios, New rams, new Cmos battery , same chime repeat.

Could this be GPU?
Really appreciate your help.

 

[2informaticos]

Still the same if disconnect power button?
Also test the board alone on the desk, nothing connected; keep only test speaker.