“Input not supported” issue on the boot screen

Hi, Recently, I built a new desktop PC which I hackintoshed fine and I have dual booted OS X and Windows 10. While I was using my full HD 60Hz TV as a monitor, everything was working fine. I mean I was able to see the AsRock boot logo and I could boot into the UEFI BIOS menu because I needed to tweak some settings. Unfortunately, the things have got changed after I switched to my Acer KA242Ybi. I am not able to see the AsRock boot logo and when I spam the f2 in order to boot into the BIOS. Instead of this I get “Input not supported”. After this message disappears, the monitor visualizes the Windows just fine. The problem is that my monitor does not visualize when I boot into OS X and I am not able to tweak my BIOS settings. Thanks for any help in advance!