CrossFire (also known as CrossFireX) allows you to install and use multiple video cards in parallel to improve the image quality or increase the frame rate of your games. SLI works by installing two or more (even identical) video cards and using them together to render the graphics faster. If one card is not available all calculations are done on the remaining card disabling SLI. Since Standoff does not support multi GPUs, you will only see it with v1.4 released recently which added support for multi GPUs.