First, this was very helpful. Thank you for the in-depth response. It was sorta number 3. My secondary monitor is a TV at 4K60 with 3:3:3 chroma rating, but it has no display port. My primary monitor is an actual ultrawide monitor with display port. The short version is that after my last driver update, Nvidia control panel reset my secondary monitor to 30 Hz. Setting the game to full screen worked to get it above 30 FPS, but the 120 Hz limiter wouldn't work. Luckily GSync took care of any tearing in cutscenes. After setting my secondary monitor's refresh rate properly, though, I can lock it in at a constant 60 in borderless windowed mode regardless of what's playing on the other monitor. Thanks again.