Well, you're doing the right thing swapping stuff around to see what works and what doesn't. Try swapping HDMI cables around also. Maybe you have a bad cable that's corrupting data at higher data rates.
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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
LG 65" OLED
RR2150 w/Klipsch SCR-2