AMD has finally launched the long-awaited successor to its dual-GPU Radeon HD 5970 and new flagship product topping its 6900 range. The Radeon HD 6990, otherwise known as Antilles, is made up of two tweaked versions of the HD 6970's Cayman XT core running at 830MHz, 3072 stream processors, 192 texture units, two 256-bit memory channels, 4GB of GDDR5 running at 5000MHz, and it consumes a maximum of 375W (37W during idle).

Not only does the HD 6990 breaks the 300W barrier dictated by the PCI-E power specification, a dual-BIOS switch on top of the card will let you crank the clock frequency up to 880MHz and maximum TDP to a whopping 450W. The typical average gaming draw is about 350 watts and 415 watts for each mode, according to AMD. In addition, the company also built a power-capping feature into the card known as PowerTune that allows the GPU to monitor its own power draw and ramp back clock speeds if needed to run within its TDP budget at the highest-possible clock speeds.

As far as cooling is concerned AMD is outfitting its latest flagship with an updated dual-slot solution featuring two vapor chambers and one center fan. The Radeon HD 6990 offers 20% more airflow and 8% better thermal performance in the same form factor as the HD 5970, despite the improved performance and increased power draw.

Of course, the main thing that anyone seriously considering buying a $700 card cares about is performance. And as it stands now the Radeon HD 6990 is certainly the fastest single-card, dual-GPU solution on the market – at least until Nvidia fires back with the rumored GeForce GTX 590.

Unfortunately, AMD didn't get us a sample card in time for a review, but we'll have it ready in the coming days. In the meantime you can check out some performance numbers over at AnandTech, PC Perspective, and Tech Report.