GWX water looks cell-shaded

[XLjedi]

Not sure what to do about this... seems it's something with my nvidia cards (latest drivers up to date). I get these gradients in the water visuals that appear smooth at first and then they decay into these ugly color patch gradients. Underwater it looks like wide bands of color, when surfaced you see an effect in the water similar to a cell shading art style effect.

Anyone have any trouble like that with nvidia cards?

Here have a look:

What's odd is even this still shot above starts out looking OK then it decays to the gradient. In fact as I type this the image looks wonderful in the text editor, but when I preview it, it looks cell-shaded... very odd.