AMD Radeon HD 6990 Review - PAGE 1

AMD has held onto their performance crown with the dual GPU HD 5970 for just over a year now, even in the face of some stiff competition from Nvidia’s 500 series. However, with rumors circulating of a dual core GTX 590 being in the works, AMD’s Northern Islands follow up to the HD 5970 has to be a gaming powerhouse to maintain their current title. This makes the launch of the Radeon HD 6990 crucial for AMD, and could be the reason behind the graphics card's extreme specifications.

To achieve the highest performance level possible, AMD has engineered the HD 6990 with a 375W thermal envelope. This allows the card to support dual Cayman XT based GPUs clocked at 830MHz. In addition each core includes 1536 VLIW4 stream processors, 96 Texture Units and 32 ROPS, which gives the card a massive computation power of 5.1 TFLOPs. The HD 6990 also comes with 4GB frame buffer (2GB per GPU) of GDDR5 memory clocked at 1250MHz (5.0Gbps effective) and runs on a x2 256-bit memory interface.

The stock specifications are impressive, but AMD has also included a unique feature on the board called "AUSUM" which is an acronym for "Antilles Unlocking switch for Uber Mode". The feature works via the dual BIOS toggle switch and is essentially a means to increase performance by modifying the GPU clock speed and peak power consumption. By default the HD 6990 runs at 830MHz and consumes up to 375W of power, but after adjusting the BIOS switch to the Uber mode, the GPU clock speed is overclocked to 880MHz and the power consumption is increased to 450W. That makes this card the first to break the 300W barrier, which is very impressive considering the HD 5970 had to be considerably downclocked to due to its 300W limitation.

At launch the HD 6990's closet competitor will be the GTX 580 and according to AMD's internal numbers, the HD 6990 has up to 67% better in game performance than the Nvidia's current flagship graphics card. It is not an entirely fair comparison as the GTX 580 is a single core solution, while the HD 6990 utilizes dual cores. The HD 6990 will launch with an MSRP of $699, which again is not necessarily a fair comparison to the GTX 580. So, at least for now it seems that the HD 6990 will be in a class of its own, with no direct competition from Nvidia. For the time being anyway.