Image Quality Comparison
Crossfire's Super AA in many ways is similar to SLI's SLI AA. Both cards render the same image with anti aliasing enabled, but the samples are taken from different parts. However, ATI is quick to point out that their Super AA sample patterns are not simply 4x or 6x sample patterns with slightly difference placement. That's because Super AA sample patterns make use of ATI's programmable sample hardware to retrieve samples for anti aliasing. So, theoretically, ATI has much better anti aliasing than NVIDIA since they can customize the sample pattern for Super AA.However, what's more ingenious is the extra modes ATI made available with Crossfire - Super AA 10x and 14x. In addition to using eight and twelve samples for anti aliasing the image you see on the screen, ATI have also found a way to provide super sampling anti aliasing as well. This works by taking the first sample from the first card and the second from the second card. So, Super AA 10x is in someways pretty similar to what you can achieve with 8xS with NVIDIA's hardware (8 MSAA samples and 2 SSAA samples).
Let's have a glimpse of what Super AA has to offer. First, here are sample patterns for 4x and 6x AA.
And here are the Super AA sample patterns (8x, 10x, 12x, 14x)
If you were looking at these images closely, you'll no doubt notice that only half the number of samples are displayed in the Super AA 8x and 12x images. This is a quirk with Super AA (or at least the current drivers) that makes it impossible for us to capture what Super AA has to offer in terms of image quality. The screenshot can only capture output from one of the cards, so only half the sample is captured. Trying to capture shots or sequences from games also yield the same results. In light of this, we will not be doing any image comparison test using games for this article. Another quirk of Super AA is that it will only work with fullscreen games and applications. That means you only get 4x AA if the 3D application or game you're running is in windowed mode.
So, do we have to settle for 'theoretically better' argument? Not quite - look again at the images. You'll notice that the lines near the edges of the screen with Super AA 10x and 14x have less aliasing than 4x or 6x AA. We can assure you that even Super AA 8x and 12x have the same aliasing as 4x and 6x (though it's slightly less but still more noticeable than 10x and 14x). We know. It's hard to believe what Super AA 10x and 14x has to offer unless you're looking at them in real life. But it looks like this will have to do for now.
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