Documents show that OpenAI signed a letter of intent to spend $51 million on brain-inspired chips developed by startup Rain. OpenAI CEO Sam Altman previously made a personal investment in Rain. Documents show that OpenAI signed a letter of intent to spend $51 million on brain-inspired chips developed by startup Rain. OpenAI CEO Sam Altman previously made a personal investment in Rain. Read More Business, Business / Artificial Intelligence, Breaking News Wired