  Observational data in the BVRI bands of the variable BL Lacertae Object S5
0716+714 is discussed from the point of view of its Power Spectral Distribution
(PSD). Analysis of the noise properties exhibited by the source. Assessment of
the validity of a turbulent model. We fitted a model of the type $P(f) = \beta
f^{-\alpha} + \gamma$ to the data for two null hypothesis and calculated the
Bayesian p parameter for the fits. Different theoretical models are discussed
and applied to these data and a special focus is placed on the
MagnetoRotational Instability (MRI). The $P(f) = \beta f^{-\alpha}$ fit
provides slopes with values ranging from 0.376 to 2.237, with medium values for
each band of $\bar{\alpha}_B = 1.756$, $\bar{\alpha}_V = 1.704$,
$\bar{\alpha}_R = 1.780$ and $\bar{\alpha}_I = 1.272$ respectively. An interval
for the calculated effective $\alpha_{SS}$ parameter is obtained to be
$[0.18,1.72]\cdot 10^{-2}$, corresponding to the order of magnitude previously
inferred through both observational and numerical investigations. Structure
function analysis, fractal dimension analysis and DFT analysis (all performed
in other studies) plus our own analysis establish that the source is turbulent
in a nontrivial way, i.e. there is "intrinsic" noise superimposed on the
deterministic behavior of the source. We propose that embedding a weakly
stochastic magnetic field component in the MRI (MagnetoRotational Instability)
framework and taking into account stochastic reconnection of magnetic field
lines might explain microvariability in AGN objects.
