The Radeon HD 6990 tackles the title with aplomb, its twin GPUs managing to double the performance of Nvidia's offering.

There's a lot to consider when measuring the overall value and efficiency of the Radeon HD 6990. First, there's the dollars per frames per second measure, which I'm summarized . In a nutshell, this compares the price of each card to the average frames per second achieved in our games tests. I included the results of the Radeon HD 6990 in its overclocked mode, for good measure.

The overall winner from a pragmatic perspective is the $350 Radeon HD 6970. It doesn't offer up nearly as impressive performance as its pricier rivals, but it sits at a price that's a bit more cost-effective. At a 1920-by-1200 pixel resolution, the Nvidia GeForce GTX 580 is technically the better deal. But once you've cranked up the resolution to 2560-by-1600, the Radeon HD 6990 offers a strong price to performance ratio -- particularly when running at the overclocked BIOS setting mode.

Next, we'll take a look at . This one is going to be a little counter intuitive: when under a full load, the Radeon HD 6990 used more power overall. But it generally did so more efficiently. To arrive at these figures, I divided the power used under load by the average results for our games tests. At the 1920-by-1200 resolution, the Radeon HD 6990 and the GTX 580 are pretty much neck and neck. They're both consuming substantially more power than the Radeon HD 6970, but they're generating plenty more frames as a result. The picture becomes much better when we crank the resolution up to 2560-by-1600 pixels. Here the Radeon HD 6990 is the clear winner, making the most of its power consumption.