Well if GM100 has been cancelled, it really isn't boding well for 20nm anytime soon;
NVIDIA Maxwell GM100:
The NVIDIA Maxwell GM100 chip would consist of 8 GPCs consisting of 24 SMX modules (3 SMX Per GPC), 384 TMUs, 6144 Cuda Cores, 8 MB of L3 Cache (8 L2 cache’s per GPC), 64 ROPs, a 512-bit interface followed by a VRAM upto 8 GB GDDR5 operation at around 6 GHz. The GM100 is supposed to replace the high-performance GK110 chip so its going to end up in both GeForce parts and Tesla parts. It will probably show up in the Tesla parts first before shipping to consumers.
Clock frequencies would be maintained at different levels for each product tier as listed below:
GeForce GM100: 930 MHz Core / 1 GHz Boost
Tesla GM100: 850 MHz (2.61 TFlops DP)
From wccftech (so bit flaky I know)