Some things to try for each monitor, if you haven’t already:
-put in “game mode”
-The benq has a HDMI RGB PC Range setting, which can be set to ‘0-255′ or ’16-235’. I think I remember reading around here somewhere that 16-235 can help with compatibility. Maybe someone more knowledgeable can chime in on how that may or may not help.
Line modes and how they appear can come down to personal preference. Assuming line5x is compatible with either or both monitors, and you prefer it, the following options can help the screen get centered/sized appropriately:
Sampling Opt -> Scroll up one and enter the Adv Timing options. Horizontal and Vertical backporch should be used first, horizontal and vertical synclen used if backporch doesn’t quite get you where you need to be.
Before Sampling Opt adjustments, set the aspect ratio to “native”, or effectively unadulterated. The manuals for both TV’s aren’t clear on what the available options are, but usually if you cycle through the options, it will be the smallest image displayed. Some times the option name actually makes logical sense, but sometimes they are named things like “Just Scan” (Westinghouse), or “Direct” (TCL).