We stumbled upon a rather intriguing post over at PCPerspective regarding recently released AMD HD 6990M performance slides as it appears that HD 6990M is not that much faster than the GTX 580M.
In case you missed it, the recently introduced AMD Radeon HD 6990M is based on Barts XT architecture and has nothing to do with its desktop dual-GPU counterpart. It is a single GPU solution that has 1120 stream processors, GPU clock set at 715MHz and up to 1.6TFlops of computing power. The GPU is paired with 2GB of GDDR5 memory clocked at 900MHz which is enough for over 115GB/s of memory bandwidth.
Apparently, AMD contacted pcper.com to let them know that benchmark results need to be changed and that new one show that the difference between the HD 6990M and the HD 6970M, and the difference between Radeon HD 6990M and GTX 580M is not that high. You can check out the article here.
After asking around, our birdies have told us that it appear that AMD was using a desktop configuration based on the HD 6870 card clocked at the same clocks as the HD 6990M for those slides and have expected the results to be identical, but unfortunately they aren't. This time around AMD's inteligence service didn't do its homework well.
The bottom line is that the HD 6990M is still faster than the GTX 580M and it all comes down to the price, which is, by the way, still on AMD's side. We checked out some prices and AMD's HD 6990M is around US $300 cheaper than the GTX 580M at least that's what we have seen on the Origin site and its EON17-S notebook and Alienware site and its M17x notebook.
So this round still goes to AMD. Of course, we are still waiting to see the "correct" slides that AMD is talking about.