One of the major reasons why AI data centers are sucking up so much power is the need to cool processors that run very hot. But Microsoft Corp. is trying out a possible solution: sending fluid directly through tiny channels etched into the chips. The technology is called microfluidics, and it’s being used in prototype systems in test conditions at the company, said Husam Alissa, who oversees Microsoft’s systems technology. The technique has been applied to server chips used for Office cloud apps...