 Two or more graphics cards can be used simultaneously on motherboards supporting SLI or ATI CrossFire technology, for nVidia and AMD based cards respectively.Both technologies allow for between two and four graphics cards, although nVidia recommends only using multiples of the same model, to be used in unison to process and render an image.A high-end graphics card will also use more electricity, or have a higher power draw, than a lower-end card.