I vaguely remember that at the dawn of the deep learning (2013 to 2014), there were talks and hopes that Xeon Phi would smash the performance of Nvidia GPUs. However, the sample people got are too late (I believe it is at the end of 2014) and the performance figures are disappointing. It might be just the software was simply not there yet unfortunately. But then the wheels moved forward and everyone started to buy Nvidia chips in their datacenters.
