Nvidia is expecting Tegra chip revenue to drop by as much as 40 percent this year, with the company indirectly blaming Microsoft's Windows RT OS for the decline. "We don't expect as much return from the investment as we had hoped," CEO Jen-Hsun Huang said on a Thursday conference call to discuss Nvidia's second-quarter financial earnings. He said the expected shortfall was related to one particular platform, and though he didn't name it, the reference to Windows RT was clear.