GK100 features 1500 CUDA Cores, GDDR 5 memory with memory interface of 512-bit, the performance is close to the dual-core GeForce GTX 590, it’s scheduled to debut in Q2 2012. While GK104 features 1000 CUDA Cores, GDDR 5 memory with memory interface of 256-bit/384-bit as well as core/Shader frequency of over 1GHz, the performance is likely to be slightly higher than that of GeForce GTX 580, it’s expected to arrive in January or February 2012.
Now, this is surprising ?? The buswidth implies the chips would still rather be big, but the performance isn't, those expectation figures go toe to toe with Tahiti and Pitcairn ones.