Overclocking to higher than 1440p60

I have a Korean monitor that I managed to overclock to 189Hz using Nvidia's control panel. The thing is, I'd rather use my AMD card as FreeSync works there (I guess Nvidia lied about supporting FreeSync). However, in CRU, it's not letting me go above 165Hz. AMD's control panel just flat out refuses anything about 165Hz.

Any ideas?