X1900 Crossfire is currently the fastest, most feature-rich, highest image quality solution I've ever tested. The performance of two X1900s is simply mind-blowing when a game works with it properly. NVIDIA has a solution with four GPUs, Quad-SLI but this isn't on the market in any numbers as of yet and will cost the buyer 2x or more a Crossfire setup. X1800 Crossfire is shown here simply to give a sense of performance if you buy a second X1800 card. X1600 Crossfire is an interesting choice in that the cards can work without a Crossfire cable.
Negatives of Crossfire include: heat, 4 slots, and cost. In a closed case the two X1900 cards read over 90C in operation with a 3D application running. That is within parameters but is a far cry from the 50-60C I've seen on the 7900 series cards. The need for 4 slots to be taken up by the two cards limits expansion options on most motherboards. The third factor, cost, means you are likely to spend over a thousand dollars on a system that will be overtaken in performance by the next generation. The future is interesting in video cards. Microsoft has delayed Vista to early next year for the consumer versions. What this portends for ATI's and NVIDIA's plans for their first Direct3D10 compliant video cards, I don't know as of yet. Traditionally, ATI and NVIDIA have released video cards on a 6 month or so schedule. We'll have to wait and see.
