ATI has made a notable comeback over the past year with some enticing GPU releases that have been able to match and also 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 HD 3870 X2 version, 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 G92 cores. - TechSpot

Diamond Radeon HD 4870 X2 Graphics Board Review

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 HD 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 GeForce GTX 280 is selling for roughly $450, giving AMD some generous pricing headroom to play with, and to actually come up with another product.

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 GPU's and sticking them on a single PCB. The Radeon HD 4870 X2 is also more sophisticated than the Radeon HD 3870 X2 on how the two GPU's are connected. The onboard GPU's communicate using a feature called CrossFireX SidePort which provides additional bandwidth between the two GPU's. However, while this feature is present in hardware, it is not enabled by default as AMD says it's not necessary at the moment.

In many ways the design of the Radeon HD 4870 X2 card resembles that of the original Radeon HD 3870 X2. Compared to the single GPU Radeon HD 4870, the X2 is a few centimeters longer. And although this sounds a bit excessive, this happens to be the same length of the high-end NVIDIA GeForce GTX 280 graphics card that uses a single GPU. The stock cooler on the Diamond Radeon HD 4870 X2 is very large, and given that it includes two large copper base plates, it is also very heavy. And a single 80mm blower fan is used to draw air from within the case, pushing it over the heatsinks fins where it will quickly warm up.

Like all multi-GPU graphics cards, the Radeon HD 4870 X2 heavily relies on the driver support to perform as intended. So, every time a new game is released it is likely that the Radeon HD 4870 X2 will not correctly support it until AMD updates the Catalyst driver. Without full CrossFire support the Radeon HD 4870 X2 is just as fast as a single Radeon HD 4870 graphics card, which is far from slow. Same goes for NVIDIA cards using SLI technology. For the most part the Radeon HD 4870 X2 is an impressive product delivering unbeatable performance. However when driver support is lacking, it will quickly turn into a $299 performer.

Personally, we are usually very skeptical about these multi-GPU technology as the results tend to vary so much, and though admittedly things have improved considerably from where we were a year ago. This makes the GeForce GTX 280 the safer bet, as it will deliver more performance in every single game, and when the next hit title comes out this is likely to be the single fastest graphics card in that game until SLI and CrossFire driver support catches up. Both the GeForce GTX 280 and the new Radeon HD 4870 X2 are amazing products, though might not always be the best option for your budget and gaming needs.

However if you want the best performance to value balance, the GeForce GTX 260 and the Radeon HD 4870 are still the way to go, and offering exceptional performance at $300 or less. We mention this because even in titles that scale very well, the Radeon HD 4870 X2 is not worth the price premium over a single Radeon HD 4870, not by a long shot. So as the $559 price tag suggests, this new Radeon is reserved purely for the most extreme gamers.