The site also came across mentions of the GM204-B1 stepping, a 20nm chip that may form the basis for the GeForce 900 series. The GeForce GTX 970 is reportedly slated for the second half of 2015.
What really caught my attention was the part where he mentioned GM204-B1 stepping. According to his sources, the B1 stepping would power future GeForce 900 series, and it’s based on 20nm process, while the A1 and A2 steppings are reserved for GTX 800 series. I found this very interesting and it actually makes sense. The only part that still bothers me is where NVIDIA uses both GM1xx and GM2xx parts on the same node, instead of splitting the them to 28 and 20nm process respectively.
However it’s not that shocking as you might think. Let me remind you that this already happened before. The G73, G92 or G94, where all split into A and B,C stepping on different fabrication nodes.