NL2 doesn't tend to force the GPU into high frequency since it doesn't demand much. Same goes for my GTX 1080 the Nvidia Driver "thinks" the demand is low so it keeps the clocks in check. What I do is I force "Prefer Maximum Performance" for No Limits 2 in the Nvidia Control Panel and I'm not sure if AMD has something similar you can do. This setting forces the GPU to stay at it's high clock speed regardless of demand but the trade-off is heat and power consumption. You can do the same thing with your CPU but setting your power mode in windows to High Performance which depending on the percentage you set will have more preference to keep the CPU at or near it's max frequency. Mine runs at 4Ghz.
I notice a pretty much locked 60FPS at 4K with my latest project "Aventador: The Revisit" with this setting enabled.