As the title says. I much prefer running the game in borderless windowed for easy multitasking on a second monitor. I have a G-sync capable monitor (which requires full screen mode) but I may sacrifice that feature to run borderless windowed. Just wondering if SLI requires the same thing.
Yep. SLI and Crossfire on Full Screen only.
Windows limitation, works around you can use app to force game windows always on top in fullscreen mode. So your game works with SLI while you can still move your mouse to another screen without minimize the game.
http://i.imgur.com/cksVt90.png
DisplayFusion or Actual Multi Monitor etc.