  The X-ray burster and dipper 4U1915-05 (also known as XB1916-053) was
observed 19 times for a total exposure of roughly 140 ks between 1996 February
and October with the proportional counter array (PCA) aboard Rossi X-ray Timing
Explorer (RXTE). We present here the detailed timing study of its X-ray
emission. The source was observed in both a high intensity/soft spectral and a
low intensity/hard spectral state. The 2-20 keV luminosities are about
1.4x10^37 and 3.2x10^36 ergs/s in the two regimes respectively (assuming a
source distance of 9.3 kpc). We confirm that 4U1915-05 is an atoll source based
on its spectral behaviour and its aperiodic variability in the frequency range
4x10^{-3}-128 Hz. 4U1915-05 displays red noise below 1 Hz, but is especially
remarkable for its quasi-periodic variability detected for the first time at
several timescales. We detect low frequency quasi-periodic oscillations
(LFQPOs) between 5 and 80 Hz, as well as high frequency QPOs (HFQPOs) between
200 and 1300 Hz. Both LFQPOs and HFQPOs frequencies positively correlate with
the mass accretion rate inferred from the position of the source on the
color-color diagram. In a narrow range of luminosity, we also detect twin
simultaneous HFQPOs separated by 348 +/- 12 Hz.
