This is just a guess, but can you specifically set the NVIDIA cards output to 4K, 60fps and see if that works? Maybe it's outputting some format that is causing the 076 to choke.
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975/7075/SMS-1
Aperion Verus Grand Towers & Bookshelves, Verus Forte Center, Infinity Surrounds, Ultra-X12
Oppo BDP-203, XBOX360, Xbox One
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