  A large set of TREESPH simulations is used to test the global morphology of
galaxy clusters and its evolution against X-ray data. A powerful method to
investigate substructures in galaxy clusters are the power ratios introduced by
Buote & Tsai. We consider three flat cosmological models: CDM,
LCDM($\Omega_\Lambda = 0.7$) and CHDM($\Omega_h = 0.2$, 1 massive $\nu$), all
normalized so to fit the observed number of clusters. For each model we built
40 clusters, using a TREESPH code, and performed a statistical comparison with
a data sample including nearby clusters observed with ROSAT PSPC instrument.
The comparison disfavors the LCDM model, as clusters appear too relaxed, while
CDM and CHDM clusters, in which a higher degree of complexity occurs, seem to
be closer to observations. A better fit of data can be expected for some
different DM mix. If DM distributions are used instead of baryons, we find
substructures more pronounced than in gas and models have a different score.
Using hydrodynamical simulations is therefore essential to our aims.
