A computer implemented method, testing system, computer usable program code, and apparatus are provided for measuring microprocessor susceptibility to internal noise A noise generator modulates a clock signal to generate noise on a targeted component within a microprocessor. A function generator executes microprocessor functions on a plurality of functional components within the microprocessor. A maximum execution frequency on the plurality of functional components is then measured and a set of frequency ranges where the functional components are susceptible to the generated noise is determined.