Although there are surely a lot of riddles that need to be solved in order to be able to manufacture a computer based on graphene as you told us, I believe that even we manage to achieve that, such a revolutionary technology concerning processing power will not be allowed to be accessed by us mere 'mortals'. A machine that will have a thousand times better results will simply cause panic in an industry that permeates most, if not all, aspects of our lives and bring such enormous losses of funds worldwide that it will not be permitted to be released. In order to gain, they must produce hi tech devices that each time are a little bit better than their predecessors, even if the mega corporations already know the avenue to make them significantly better. Let's all hope that I am somehow mistaken and such amazing discoveries find a way to drastically improve the quality of our lives.