CompaniesSAN FRANCISCO, March 12 (Reuters) - Lip-Bu Tan may be one of the most powerful technology executives you've never heard of. As he steps into one of the highest-profile jobs on the planet, CEO of troubled, storied chipmaker Intel, his performance will be on full display.Tan, named Intel CEO on Wednesday, faces an enormous challenge in turning around the operations of a company that put the "silicon" in Silicon Valley.The Technology Roundup newsletter brings the latest news and trends str...