Power spectra of SS Cyg in outburst obtained from a collection of archival RXTE data listed in Table 1. The PDS at different times are ordered as the quiesence on the top lefthand side, the X-ray peak on the top righthand side, and the X-ray dips during the optical peak on the bottom lefthand side. On the bottom righthand side, the PDS of SS Cyg in quiescence and during the X-ray suppression (optical peak) is shown for comparison. The solid lines show the fit with the propagating fluctuations model for the top figures and for the PDS of the X-ray dips two Lorentzians along with the propagating fluctuations model are used to achieve the best fitting results. The reduced χ² values of the fits are 0.62, 1.5, and 0.4 for the quiescence, the X-ray peak and the X-ray dips, respectively.