When AMD released the Radeon HD 2900 XT in May of last year, we were left with a bitter taste in our mouths. Not because the product was all that bad, but because it seemed AMD was content to leave NVIDIA uncontested at the high-end of the 3D graphics card market. If you remember, when the Radeon HD 2900 XT launched AMD had targeted the mid-range GeForce 8800 GTS, and not NVIDIA's high-end GeForce 8800 GTX or Ultra. It seemed as if AMD just didn't want to be in the fight for 3D graphics supremacy any longer and enthusiasts like yourselves, who seek nothing but the highest performing products, were left with only a single option leaving AMD in the cold. - HotHardware

ATI Radeon HD 3870 X2 CrossFireX Graphics Review

Thankfully things have changed in the last few months. After the R600 shipped, AMD's engineers went right back to work. And in November AMD released the Radeon HD 3800 series of products, which were based on an updated GPU design that performed much like the R600, but with more moderate power and thermal characteristics. The new GPU, formerly codenamed RV670, still wasn't quite as fast as NVIDIA's higher-end offerings, but its low power profile gave AMD the ability to engineer the product we will be showcasing today. The Radeon HD 3870 X2 was codenamed R680 throughout its development.

At first glance, the Radeon HD 3870 X2 looks much like AMD's previous high-end GPU offerings. The card features ATI's signature red PCB with an up close and personal look into Ruby's eyes emblazoned on the fan shroud. Flip the card over, however, and it becomes abundantly clear that the Radeon HD 3870 X2 has a lot going on under its cooler. As we've already mentioned, the Radeon HD 3870 X2 is powered by a pair of RV670 GPU's, the same chips used on the Radeon HD 3870. The two GPU's are linked together on the PCB itself through a PCI Express fan-out switch from PLX, quite different than seen with the GX2 solution.

That switch takes the sixteen PCI Express lanes coming from the PEG slot and distributes them to both of the GPU's. We should note, however, that although the RV670 GPU has a native PCI Express 2.0 interface, the on-board switch is PCI Express 1.1 compliant only. Also note that the Radeon HD 3870 X2 has only a single CrossFire edge connector along the top of its PCB. It has only one because the other connection is already utilized on the PCB. Although the Radeon HD 3870 X2 is equipped with a CrossFire connector, at this time drivers are not available that will allow end users to link two of these cards together.

The Radeon HD 3870 X2 isn't simply two Radeon HD 3870's fused together on a single PCB. The GPU's on the Radeon HD 3870 X2 will be clocked at a minimum of 825MHz, up from the standard Radeon HD 3870's 775MHz. The Radeon HD 3870 X2's frame buffer memory will be clocked lower, however, 1.8GHz versus 2.25GHz. What this means is that in applications that are limited by shader performance and fillrate, the X2 should be faster than a pair of Radeon HD 3870 cards running in CrossFire mode. Conversely, in applications that are memory bandwidth bound, the dual card CrossFire configuration should be faster.

We're cautiously optimistic about the Radeon HD 3870 X2 graphics accelerator. On one hand, our benchmark results are undeniable. The card simply performed well throughout testing and it marks AMD's re-entry into the high-end 3D graphics card market. During the course of testing, however, ATI supplied us with three different sets of drivers, with each set either improving performance or fixing bugs. This brings us to an important point. Because the Radeon HD 3870 X2 is essentially CrossFire on a card, the X2's performance is determined by how well the card's drivers scale in a particular game.

If a new game hits store shelves and the drivers don't recognize the executable, the $449-499 priced Radeon HD 3870 X2 will perform much like a single Radeon HD 3870 that is half the price. ATI assures us their software team will try to minimize this situation, but it will be an issue at some point in time no matter how hard they work unless a somewhat universally compatible multi-GPU rendering technique is devised. This is something you must be aware of if you're contemplating the purchase of Radeon HD 3870 X2. For now, AMD should be proud of their achievements and showed they are able to strike back.

We're sure many ATI loyalists are going to look at today's launch as a huge success. Ultimately though, the real long-term value of the Radeon HD 3870 X2 will be determined by AMD's driver team. If they work closely with game developers and consistently improve performance and scaling for existing and upcoming games, then the Radeon HD 3870 X2 is worthy of praise. If the drivers can't keep pace with game releases, and users have to wait weeks, or even months to fully utilize their graphics card, that would be a great disservice. We're hoping for the best, because the hardware is impressive indeed.