Yes, P2P requires cc2.0 or higher GPUs, and on windows requires a TCC driver mode:
Since as of today, TCC is not supported on GeForce, then my answer above was wrong or misleading. I wouldn’t expect a P2P test on GTX Titans to pass on windows, today, on CUDA 7.0.
Although I can’t immediately document this, I should further clarify that P2P is supported between like devices of cc2.0 or higher. P2P is not necessarily supported between a cc2.0 and a cc3.0 device, for example.
However, the cards mentioned in this thread (Titan and Titan Black) should satisfy the requirement of “like devices”, and so, under linux, I would expect that P2P transfers between those two cards is possible. However, the first message in this thread states “windows platform only”