Custom Resolution Utility (CRU)

[chipzen]

I'm trying to set a resolution that I used on my Nvidia GPU before (1920x1440 on a 1080p monitor), but on AMD, it won't work. So I tried CRU, but when I try to set the refresh rate to 240, it goes red and I can't press ok. Any idea why? Super resolutions work just fine at 240Hz so I don't understand at all. Any sort of response will be appreciated, thanks.

P.S. If you ask me why I want to use the resolution, it's for gaming. I don't need to hear your opinions on whether or not I should use the res because I have gotten enough of those elsewhere.