How to fix screen tearing in Like a Dragon: Ishin! with high-end RAM?

It's infuriating; I bought 6800MHz top-tier RAM, but it's laggier than low-frequency RAM in Ishin!, with obvious screen tearing. I tried forcing voltage to 1.45V in BIOS to maintain 6800MHz, but it led to a Blue Screen of Death after ten minutes—a suicidal move. I used the GamePP BIOS Load-Line Voltage Adjustment Wizard to downclock to 6400MHz and set voltage to 1.38V per GamePP. AIDA64 confirmed latency converged to 68-72ns.