Alternate Frame Rendering (AFR) is a technique of graphics rendering in personal computers which combines the work output of two or more graphics processing units (GPU) for a single monitor, in order to improve image quality, or to accelerate the rendering performance.
This technique is useful for generating 3D video sequences in real time, improving or filtering textured polygons and performing other computationally intensive tasks, typically associated with computer gaming, CAD and 3D modeling.
AFR belongs to a class of parallel rendering methods, which subdivide a four-dimensional image frame[dubious – discuss] sequence (x,y,z and time) into smaller regions, each of which is then assigned to a different physical processor within a multi-processor array.
Also, the multiple processors can be implemented within a single video card or separate video graphics cards can be combined, subject to the motherboard and I/O slot limitations.
When separate video cards are used, they must be specifically designed to allow a "cross-link" between them.