A cumulative update for Windows 10 is currently making the rounds and that is potentially bad news for gamers with multi-monitor setups. Microsoft lists a couple of known issues that are tied to the update, one of which can cause abnormal behavior when running 3D rendering apps (mostly games) on systems with more than one monitor. Such users

Source: Hot Hardware – Latest Windows 10 Cumulative Update Hoses Multi-Monitor Support For Gamers