ATI has made a notable comeback over the past year with enticing GPU releases that have been able to match and sometimes surpass Nvidia's offerings in terms of performance, power consumption and value.

However, that's not to say Nvidia has been sitting duck all this time, as they have promptly answered anything ATI has thrown at them. For example, earlier this year when ATI was claiming back the performance crown with the dual GPU Radeon 3870 X2, Nvidia was quick to react with an even more impressive and better performing card. The GeForce 9800 GX2 followed the same dual GPU path, using Nvidia's SLI technology and a pair of GeForce 8800 GTS 512 GPUs.

Then two months ago Nvidia launched their latest generation graphics cards consisting of the GeForce GTX 280 and GTX 260. Yet the Radeon HD 4870 and 4850 have proven to be excellent counterparts, offering similar levels of performance for a fraction of the price.

As things stand today, the GeForce GTX 280 is the fastest single GPU graphics card available, while the standard Radeon HD 4870 is not too far behind it. Yet the Radeon costs less than $300, while the GTX 280 is selling for roughly $450, giving AMD some generous pricing headroom to play with.

So, trying to make the most of this situation, for $559 AMD has come up with the Radeon HD 4870 X2, which follows the same premise of previous generation X2 cards, taking two of the latest Radeon GPUs and sticking them on a single PCB. A terrifying prospect given the power of today's graphics processors. The Radeon HD 4870 X2 boasts an enviable combined processing power of 2.4TFLOPS, 60 Gtexels/s of bilinear filtering, and courtesy of some highly clocked GDDR5 memory, 230GB/s of memory bandwidth.

The Radeon HD 4870 X2 is also more sophisticated than the 3870 X2 on how the two GPUs are connected. The onboard GPUs communicate using a feature called "CrossFireX SidePort" which provides additional bandwidth between the two GPUs. The total interconnect bandwidth of 21.8GB/s provides about three times more bandwidth between the GPUs compared to the older 3870 X2. However, while this feature is present in hardware, it is not enabled by default as AMD says it's not necessary at the moment, and can be enabled later on the drivers should future titles require the additional bandwidth.

As for the card pricing, it's important to note how buying the 2GB version of the Radeon HD 4870 X2 is cheaper than purchasing two Radeon HD 4870 1GB graphics cards. This could give users an added incentive to spend all their hard earned cash at once rather favoring a Crossfire configuration and leaving the second card as a possible upgrade down the path.

Today's Radeon HD 4870 X2 review sample was manufactured by Diamond and features the full 2GB of memory. We are told that eventually a 1GB version might arise, while a slightly slower and more affordable Radeon HD 4850 X2 will also carry 1GB of memory per GPU (2GB total) and is set for release later this month.