The second pcie slot on the biostar ta970 is only x4 speed but that should be fine for low end cards. Nvidia and amd? Just install both drivers. If you only have 1 monitor, you have to change which gpu is connected to it. Some monitors you can connect 2 cables, 1 from each gpu and just change the input selection on the monitor. With multiple monitors, just change which monitor is the main and the gpu connected to it will be used for the game.