Well the usual things to suggest first in a situation like this is to eliminate the possible variables to come to a fresh starting point for troubleshooting.
Cleanly remove any and all remnants of the graphics drivers, and reinstall them.
Confirm the issue does or does not happen during single monitor use. Confirm it doesn't happen with the Asus, then confirm it doesn't happen with AOC, or if it does, report the circumstances. Then go back to two monitors connected and confirm it does happen and is repeatable, or if it no longer happens (can hope). Depending on the results of the single monitor tests, it may lead you to testing the monitor's cables, their connections at both ends, different connectors on the monitors, swapping cables, etc. You'll want to rule out all of these possibilities first because they're hardware. Confirming all of that is good to go is the first start.
I wouldn't be surprised however if some Tom's genius pops in and says, "oh do this and yer good to go".