Well, out of a pure fluke and messing about for a long time, then giving up when I had at best 38 Mins frame repeats which was livable...
I came across this post on a random Google search...
1. Go to Nvidia Control Panel
2. Change the Resolution to 23 HZ (I left this one at 24hz and it made no difference)
3. Create Custom Resolution With Following Settings:
Horizontal Pixels: 1920
Vertical Lines: 1080
Refresh Rate: 23
Timing:
Standard: Manual
Horizontal:
Active Pixels: 1920
Front Porch(pixels): 638
Sync width(pixels): 44
Total Pixels: 2750
Polarity: Positive
Vertical:
Active Pixels: 1080
Front Porch(pixels): 4
Sync width(pixels): 5
Total Pixels: 1124
Polarity: Positive
Hz: 23.976
I'm using a 1050 and 390.77 drivers, and I am now getting 8 hrs + without a frame repeat on 1080p, and 2160p->1080p.
I never did get the MadVR ones to work, well any better than the Nvidia, and CRU and the likes were a pain for me for some reason.
It takes a minute and actually sits at 23.9755 ish, and the deviation locks out at 0.00230% or something like that and all good.
Sorted.