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ATI has been waiting a long time for this moment. nVidia has been dominating the top-end of the graphics card market for nearly two years now and, although ATI has come back strong with its competitively priced HD 4870 and HD 4850 products, there's nothing quite like being able to claim the top spot.
Enter, then, the ATI HD 4870 X2 (codenamed R700), the fastest graphics card in the world. Well, that's what ATI says - we'll be putting these claims to the test later on. First, though, there's a few details to get out the way.
As you may have guessed from the 'X2' on the end, this card uses the same performance boosting method employed by the HD 3870 X2. Namely, taking two graphics chips, slapping them on the same card and using the wonders of Crossfire to make them work together to increase the card's overall performance. The big difference between this card and a standard dual card Crossfire/SLI solution is the fact that the X2 is platform independent so will work on any motherboard with a x16 PCI-Express slot, whether the chipset the motherboard uses is Intel, AMD, or nVidia.
Now one problem with this method of performance boosting is that it requires games and drivers to be written to take advantage of the two chips. This can lead to new or obscure games seeing little benefit from the second chip or even in the worst case scenarios lead to games not working at all. So, we were hoping that ATI might have come up with a magical way of making Crossfire on the HD 4870 X2 work seamlessly so performance and compatibility is consistent across all games. Unfortunately this isn't the case so there are still all the potential pitfalls that have plagued multi-GPU solutions to consider before buying this card.
With that said, the reasons for buying this card are still very compelling. I mean, just look at the stats.
Need I say more?
Ok, I suppose I'd better.
Some of the crazy figures that result from strapping two RV770s (the codename of the chip used in the HD 4870) together really start to become meaningless - a theoretical 2.4TeraFLOPs of processing power is, as ATI is keen to point out, double the performance of the fastest super computer in the world in 1996. Cool, no doubt, but of little real world relevance. What is most important to note is despite the doubling up of most numbers, the HD 4870 X2 should only bring about 1.6 - 1.8 times the performance of a single HD 4870.