Question Displayport no signal when opening games

[P0rti]

Hey everyone I have a asus rog xg248 . When I'm opening a game it's getting randomly losing signal and the only solution I have is close monitor and open again that solves it but I wanna know why this is happening when game opens? Other than that also in desktop waiting idle monitor goes low hz like 200 hz or something and this is also randomly. Is there any fix for that other then I have?

If it helps my pc specs

1660 Ti
I5-8400
16 Gb Ram

 

[rgd1101]

brand and model of the psu?

 

[P0rti]

brand and model of the psu?

xigmatek shogun g 750w 80 plus gold