We present the broadband X-ray power spectral density function ( PSD ) of the X-ray-luminous Seyfert 1.2 NGC 7469 , measured from Rossi X-ray Timing Explorer monitoring data and two XMM-Newton observations . We find significant evidence for a turnover in the 2–10 keV PSD at a temporal frequency of 2.0 ^ { +3.0 } _ { -0.8 } \times 10 ^ { -6 } Hz or 1.0 ^ { +3.0 } _ { -0.6 } \times 10 ^ { -6 } Hz , depending on the exact form of the break ( sharply-broken or slowly-bending power-law , respectively ) . The “ surrogate ” Monte Carlo method of Press et al . ( 1992 ) was used to map out the probability distributions of PSD model parameters and obtain reliable uncertainties ( 68 \% confidence limits quoted here ) . The corresponding break time scale of 5.8 \pm 3.5 days or 11.6 ^ { +17.5 } _ { -8.7 } days , respectively , is consistent with the empirical relation between PSD break time scale , black hole mass and bolometric luminosity of M ^ { c } Hardy et al . Compared to the 2–10 keV PSD , the 10–20 keV PSD has a much flatter shape at high temporal frequencies , and no PSD break is significantly detected , suggesting an energy-dependent evolution not unlike that exhibited by several Galactic black hole systems .