Conclusions
With a total of just seven games tested, we can ruthlessly boil down the Radeon HD 6990 and its competition to a simple price-performance scatter plot, like so:

We've taken the results from the highest resolution or most intensive setting of each game tested, averaged them, and combined them with the lowest prevailing price at Newegg for each of these configurations. Doing so gives us a nice distribution of price-performance mixes, with the best tending toward the upper left and the worst toward the bottom right.

At present, in the suite of games we tested, AMD looks to have a performance advantage at several key price points. That may be a little jarring if your expectations were set several months ago, when we had something close to parity between red and green. We believe AMD has come by it honestly, delivering some impressive performance gains in recent driver releases. One of those changes, AMD tells us, is a revised resolve mechanism for multisampled antialiasing that improves frame rates generally when MSAA is in use—like in nearly all of our test scenarios—particularly in games that use deferred shading schemes. AMD's driver developers have made some notable progress in CrossFireX multi-GPU performance scaling, too. SLI scaling has long been one of the hallmarks of Nvidia's SLI, but AMD has closed that gap in recent months.

Of course, both of these changes benefit the Radeon HD 6990, which has no equal in a single-card package. This is the planet's fastest single video card, supplanting the Radeon HD 5970 that came before it. The 6990 is even faster than two GeForce GTX 570 cards in SLI, which cost about the same amount, and the 6990 draws less power under load, even in AUSUM uber mode. Add in the 6990's rich array of display outputs, and there's no question Nvidia is severely outclassed at this lofty $700 price point. We just hope the 6990 isn't quite as difficult to find over the next year as the Radeon HD 5970 was during much of its run. We do believe TSMC's 40-nm supply problems are behind us, so we're optimistic on that front.

Having said that, we can't help but notice that AMD does offer a more attractive solution in terms of price, performance, and acoustics in the form of dual Radeon HD 6970 cards. You must really covet slot space—or have designs for a dual-6990, four-way CrossFireX rig—if you pick the 6990 over two 6970s. Not that there's anything wrong with that.

We also can't avoid noticing Nvidia still owns the title of the fastest dual-GPU solution on the market, in the form of two GeForce GTX 580s in SLI. And we have some clear indications that Nvidia may be cooking up an answer to the Radeon HD 6990 based on that same technology. The challenge Nvidia faces if it wants to dethrone the 6990 is, of course, power draw and the related cooling required. Given that two GTX 570s are slower than a single 6990 and draw more power, the GeForce team certainly has its work cut out for it. Besting the 6990 will have to involve some deep magic, or at least solid progress on multiple fronts.

Or, you know, a triple-slot cooler.