Borderless Mode not smooth

Hello,

I've been trying to play on Borderless Mode but somehow it feels not smooth even though I have stable FPS of 144 (uncapped at 300-450). Changed some Nvidia settings, tried the Hextech repair tool, set the priority in the taskmanager on High, set all my graphicsetting ingame on low, but nothing seems to work so that's why im asking here now.

Thanks for the help already.

I dont know if its a bug but i havent found another suitable Sub-Board