This is for selecting the graphics card vMix will use on systems with multiple graphics cards installed.
For best performance this should match the graphics card that monitor displaying the vMix interface is attached to.
For laptops with hybrid graphics (also known as Optimus), only the graphics card selected in the Nvidia control panel
will be visible here. In this case, you can instead control Integrated or Dedicated graphics use in vMix from the Nvidia control panel, or equivalent control panel
if using a different graphics card vendor.
Low Latency Capture
This will reduce the latency of Camera inputs by approximately one frame.
This will substantially increase the load on the graphics card and may lead to dropped frames under heavy load, so it should used with caution.