Update Jan 3rd, 2012 21:45: According to a story over at Brightsidenofnews.com, Chris Hook, currently „Head of WW Social Media and Ecosystem Communications” at AMD flat out denied, saying
There are no hidden cores…
The guys over at chiphell show the following picture, which at first glance lists quite a few SKUs, Sapphire apparently plans. The OC-models of the Toxic-brand are supposed to reach an impressive 1335 MHz for the core. But above, there are two models seemingly cancelled. Under the black ink crossing out part of their specification, you can just barely make out the number: 2304.
That's right: 2304 shaders, which would equate to 36 Compute Units and thus a 12.5 percent increase in performance - linear scaling assumed. This would be in line with what industry sources suspected, but only dared to whisper. It would also help to bridge the gap between a large ASIC produced on a brand new manufacturing process and a yield large enough to warrant availability from january, 9th 2012. Additionally, the document photographed also mentions a planned 1000 MHz clock for the original configuration.
Now, that leaves the option of a higher performing variant in order for AMD to counter Nvidia's GK104-chip which is expected in Q1 2012 if need be and it also explains the comparatively low gains in gaming performance when put in relation to the massively increased transistor count. That said, AMD probably still needs to do more work on their front end in order to get a more linear scaling with increasing numbers of functional units.