Well after some messing around I've now got my monitor setup nicely for different content I watch on this.
Used ToastyX's 'AMD Pixel Clock Patcher' and 'Custom Resolution Utility'
Now I've got my G2120HD going to these with madVR's automatic display mode change
75Hz for 25 stuff (also desktop use of course)
71.928Hz for 23.976 stuff
59.94 for 29,97 stuff
and last but not least 48Hz for 24 stuff.
Still gotta do some finetuning when I have the time but works great