I stand corrected.... I had to test it again, and indeed, 446.14 is working for me also from a few tests.
Need to see if it holds, but i recall it was having issues sticking to 12bit for 23.976 and i often had to correct that in Nvidia Configuration.
But so far, so good!
Now i'm still baffled why the latest drivers work fine in windowed mode and why MPC-HC, lav filters and madVR combo is working without issues...
But TNX for the driver hint
More info here and madshi's reply.