random screen flicker / flashing

[eltrasimaco]

Hi, I have permanent raspi kiosks displaying web content upon 46'' samsung screens with 1366x768 resolution
With the old samsung screen sets ( 5+ years) everything is working OK
With the new samsung models, it begins to flicker randomly; rebooting the screen OR the raspberry fixes the problem, but two or three hours later, it begins again: screen "flashes" every two or three seconds
Changed HDMI cable, PSU, sd, tried several hdmi_boost values, tried several native screen parameters, all without result.
Any hint, please? i'm really lost about this problem
TIA

[eltrasimaco]

... really lost about this problem ...