[pixelpoet]

> It's way more likely that AlphaGo is trained on spare time, the cost for the hardware is sunk anyway, so only the cost for upkeep is real.

Not quite, power is quite expensive and basically all modern computers use far less power at idle than going full bore saturated with multiply-add instructions and perfect memory streaming.

Having said that, I agree that there is a substantial cost efficiency gain if they can schedule it during periods of inactivity.