Japanese site 4Gamer.net reports that the entry-level GK107 card could be the first model of Nvidia's new 28 nm GPU series and arrive with a 128-bit memory interface as well as GDDR5 memory. The GK106 will follow as a mainstream version and apparently use the same GPU core, but support a 256-bit interface as well as PCI Express 3.0, instead of PCIe 2.0 in the GK107.
A performance version GK104 is due in Q3 and will use a 384-bit memory interface and integrate 1.5 GB of memory. According to 4Gamer.net, the card will deliver a single-precision floating point performance of 2 TFlops. A high-end GK110 apparently scheduled for Q4 uses two GK104 cores and deliver about 4 TFlops while the flagship model GK112 isn't scheduled to be released before 2013 and arrive with a 512-bit GDDR5 interface.
Nvidia declined to confirm the information published by 4Gamer.net.