ok, when i wrote my first comment I had this bad readings with 19.11.1, but just installed 19.11.3 , in fact still have ram fluctuation at idle but it's max 1150mhz , so it's ok , as i game allways at 1200 , (in games it holds 1200 without going beyond , so no bug in game)
noticed that overclocking with "morepower" is working again too , so finally it's ok for me