The rapid x‐ray variability of black hole candidates and neutron stars with high, low, and very low magnetic fields is compared. Similarities in the properties of the variability between source types suggest that similar physical mechanisms underly some power spectral components seen in common in neutron stars with various magnetic‐field strengths and black hole candidates. Other components appear to be unique for magnetized neutron stars. Suggestions are made for the sites of origin and generation mechanisms of these power spectral components. ©1994 American Institute of Physics.