AMD has finally revealed the full details of its dual-GPU graphics board, the Radeon HD 6990 - and it's an absolute beast, packing two specially screened Cayman GPUs into a single PCB design which it claims is the fastest board on the planet.The AMD Radeon HD 6990 is powered by two Cayman-series GPUs, originally destined for the Radeon HD 6970 but screened during the manufacturing process to ensure they will run acceptably at 880MHz - an odd figure, given that the official specs state the Radeon HD 6990 runs at 830MHz, but one that will soon make sense.The two GPUs give the Radeon HD 6990 an impressive 3,072 stream processors, making this board a tempting one for those who are looking to squeeze as much GPGPU power into their systems as possible - and, given that the board only takes up the standard dual PCI Express slots, could mean that when prices drop it becomes a popular model for high-performance computing use.
As we saw from the display models at CeBIT this year, the Radeon HD 6990 features a pair of eight-pin power connectors - required due to the board's impressively high 375W maximum power draw. The use of two eight-pin connectors gives the card some overhead, however - which AMD has put to good use, and we're not just talking about the generous 4GB of GDDR5 graphics memory.
A switch on the top of the board, we were told during a briefing with AMD, allows the user to switch between standard mode - during which the board runs at 830MHz - and Uber Mode - which switches things up to an impressive 880MHz. This, however, increases the power draw quite impressively - making the ~375W design into a ~475W design. As a result, AMD will be forcing its hardware partners to place a sticker over the switch warning users to ensure they have an adequate power supply or risk damaging their hardware.
All this power results in increased heat output, and AMD has completely redesigned the cooling system compared to previous Radeon 6000-series designs. A full-contact heatsink keeps the memory cool, while a single central fan blows air both left and right through the dual-vent design, with a GPU located either side to ensure each gets a supply of fresh air. The GPUs are also treated to a phase-changing pad which, the company claims, means improved contact between the heatsink and the GPU compared to the thermal grease used in previous editions.The back panel has had a complete redesign in the 6990, ditching one of the DVI outputs in favour of a massive four DisplayPort connectors. Those without DisplayPort-capable hardware will be pleased to hear that AMD is bundling a DisplayPort to HDMI adaptor and a pair of DisplayPort to DVI adapters in the box. The new layout enables an additional trick, too: AMD's EyeFinity now supports a new native five-monitor portrait layout.
To squeeze extra performance out of the board, AMD has introduced a feature it calls PowerTune. Designed to adjust the power draw of the card on a millisecond-by-millisecond basis, PowerTune allows the Radeon HD 6990 run faster in its 375W window than would otherwise be the case - resulting in around an extra 20 frames per second on popular titles, including Metro 2033, Medal of Honor, and Alien vs. Predator.
The board also includes a new feature called morphological anti-aliasing, a post-processing function powered by DirectCompute which delivers full-scene anti-aliasing - designed to reduce the number of jagged edges visible on objects and surfaces - with improved performance compared to the traditonal super-sampling method. Impressively, MLAA can be enabled for all DirectX 9, 10, or 11 titles - including older games that don't feature native support for anti-aliasing technologies. This is joined by EQAA, or Enhanced Quality Anti-Aliasing, improving the overall quality of all anti-aliasing technologies still further.
There's no denying that AMD's latest board is impressive, but so far the only official benchmarks released compare it to Nvidia's GeForce 580 GTX - a single-GPU board. With Nvidia rumoured to be launching the dual-GPU GeForce GTX 590 in the near future, the high-end graphics market looks to be getting extremely interesting.
Tags: cayman (gpu family), displayport, radeon 6990, amd