I've already reported that NVIDIA would unveil its new Pascal-based Titan X successor at its GPU Technology Conference in early April, but we should expect a "surprise" Pascal demo at GTC according to the new rumors.
NVIDIA co-founder and CEO Jen-Hsun Huang will be kicking off his usual opening keynote on April 5 at 9AM PST, where we should be greeted by the next-gen GeForce GTX Titan X, based on the Pascal architecture. Now, NVIDIA is set to hit the 16nm process with Pascal, as well as using HBM2 - so we might see the Titan X successor unveiled, but not launched at GTC. When will NVIDIA launch the Pascal-based Titan X successor? According to the rumors, sometime around June - just like it did with the GTX 980 Ti last year.