Need help with monitor hz

So recently i just got windows 11 after i upgraded my mother board and everything is going fine exept one thing, whenever i go on steam, put my mouse over my taskbar or just open apps my monitor keeps going into 60 hz for a couple of seconds and sometimes not switching at all. I even checked the settings and it still shows that my monitor is set up to 240 hz even when it keeps going to 60, can anyone help?