The majority of high-end gaming systems sold throughout 2005 were equipped with nVidia GeForce 7 series graphics cards. nVidia's GeForce 7800 GT and GTX were the twin pair of products which dominated this market, no doubt with the help of nVidia's SLI technology. ATI struggled throughout 2005 to get their R520 and R580 graphics chips to market, the latter of which finally emerged into the market in early 2006. With the release of these chips and the subsequent Radeon X1900 XT/XTX series of cards, ATI regained the top spot in terms of single card gaming performance. However, ATI's multi-GPU technology, Crossfire, still lacks the appeal of nVidia's well-established SLI technology.