By Che Pan and Casey Hall BEIJING/SHANGHAI (Reuters) -Demand in China has begun surging for a business that, in theory, shouldn't exist: the repair of advanced Nvidia artificial intelligence chipsets that the U.

As the top chip company, Nvidia's chips are in high demand from the largest companies, like Amazon and Microsoft, that are building out huge AI businesses. They themselves are serving other giants with AI tools and services in partnership with Nvidia, offering access to the chipmaker's powerful technology.