We have investigated the X‐ray variability of Sco X‐1 on its normal branch when several simultaneous noise components and quasi‐periodic oscillations (QPOs) are observed with theRossiX‐ray Timing Explorer (RXTE). The upper kHz QPO frequency is anti‐correlated with the X‐ray flux on the time scales of the very low frequency noise (VLFN) and the normal branch oscillation (NBO), while the lower kHz QPO strength seems anti‐correlated with the NBO flux, opposite to that of the horizontal branch oscillation (HBO). We summarize the overall picture of decomposing the X‐ray variability of Sco X‐1 on its normal branch into these noise components and QPOs, and discuss the consequences for the X‐ray variability models. © 2004 American Institute of Physics