Question Can't make custom resolution

[respeccbanana]

So I would like to make custom stretched resolution like 1280x1080 but everytime I would like to make it I got this error: "Resolution not supported, change the resolution of the external device." I have AMD RX 590 Gpu and I made custom resolution at AMD radeon settings but everytime I got that error... I am able to make 1440x1080 and 1600x1080 but not any other custom resolution. I have turned off GPU Scaling and set Scaling mode to Full Panel. My monitor is Samsung T24B301. Can somebody help? Thanks

 

[Ralston18]

Verify that the Samsung T24B301 monitor supports that resolution.

Do you have the User Guide/Manual?

If not check Samsung's website. I found the ("a") manual but it did not seem to be an applicable match to your model.