We have analysed archived Ginga data on the Z source Sco~X-2 ( GX~349+2 ) .
We present the first detailed investigation of its X-ray fast-time variability , as a function of position in the Z track .
During the two-day observation over the period 5–7 March 1989 , the source was in the so-called flaring branch , and the lower part of the so-called normal branch .
We found broad peaked noise with a centroid frequency and width of \sim 4–7 Hz and \sim 6–12 Hz respectively .
The peaked noise was strongest in the lower flaring branch , with a maximum fractional rms amplitude of \sim 3 \% .
We conclude that it is not a manifestation of atoll source high frequency noise , as had been suggested , and compare it with the power spectral features seen in other Z sources .
We find that the peaked noise is markedly different to the quasi-periodic oscillations found in the normal and flaring branches of Sco~X-1 ; however it bears some resemblance to that seen in the flaring branch of Cyg~X-2 at low overall intensities .