A version of AlphaGo that beat Fan Hui ran on a single machine, but a very beefy one (48 CPUs and 8 GPUs).

Unless they can optimize it quite a bit, we won't be seeing this on a mobile phone anytime soon. Perhaps you'll be able to pay a good hourly rate for the cloud version.

A mobile phone version will still trounce the current AIs like CrazyStone considering the single machine version is competitive with the cluster (can take some games off of it)

Well, we can't answer that question at this point. We do know that the system is more powerful than a human, so the question becomes "How much hardware can we take away and still be better than the best". That sets the hardware floor we have to reach.

The current answer is, still a long way off. With massive forecasts in GPU power over the next few years it may be reasonable for people to have desktops in their home with this kind of power possibly within a decade. I won't even give a timeline for phones because of the power requirements.

I think this is a good guess. 280 GPUs in a single Desktop. It will take at least 10 years.

Perhaps longer given the restrictions (and huge problems) in further down scaling of the known silicon technology. GPUs are now at 28nm and the newest Intel CPUs on 14nm.

NVIDIA is projecting 5-10x gains in Deep Learning performance out of their next generation hardware (Pascal) [1]. Might be sooner than you think.

[1] http://techreport.com/news/27978/nvidia-pascal-to-feature-mi...