ATI's Multi-GPU Solution: CrossFire

CrossFire vs. SLI

So, the question everyone wants answered is: how does CrossFire compare to SLI?

Well, it's very difficult to answer this question with no performance numbers. Obviously, if one solution outperforms the other in any significant way, pluses and minuses based on feature set fade into the background. But feature set is all we have to go on right now as we don't have final hardware in hand for a proper comparison.

One highly debated issue is ATI's claim of broader compatibility than NVIDIA. Our understanding of "compatibility" is that any title will be able to run in at least one CrossFire mode. This includes not only the performance enhancing modes, but the quality enhancing modes as well.

It doesn't seem plausible to us that ATI has found a way to split the graphics work between two cards in a more compatible way than NVIDIA. But enabling ATI's Super AA modes eliminates the need to split the work. With each card rendering the complete scene (only using different AA sample points), ATI can effectively offer something to all titles where NVIDIA cannot. Those who choose not to enable AA for these titles will likely see a trend similar to NVIDIA's performance - more than one card won't help performance.

As it is really difficult to tell from briefings, presentations, and white papers exactly where the lines of compatibility are drawn, we will simply have to wait until we get our hands on the cards before we finalize our conclusions.

Looking at all the features, if performance ends up equal or in ATI's favor, we have to consider CrossFire the more interesting solution. The flexibility of easily using multiple displays along side multi-GPU performance combined with the option of enabling higher quality AA (including rotated grid SSAA) is impossible to ignore. Add to that the ability to upgrade existing hardware without needing an exact match and we are sold.

Here's to hoping the performance of CrossFire lives up to the potential of its featureset.