  Using the statistics of pixel optical depths, we compare HI, CIV and CIII
absorption in a set of six high quality z ~ 3-4 quasar absorption spectra to
that in spectra drawn from two different state-of-the-art cosmological
simulations that include galactic outflows. We find that the simulations
predict far too little CIV absorption unless the UVB is extremely soft, and
always predict far too small CIII/CIV ratios. We note, however, that much of
the enriched gas is in a phase (T ~ 10^5-10^7 K, overdensity ~ 0.1-10, Z >~0.1
Z_sol) that should cool by metal line emission -- which was not included in our
simulations. When the effect of cooling is modeled, the predicted CIV
absorption increases substantially, but the CIII/CIV ratios are still far too
small because the density of the enriched gas is too low. Finally, we find that
the predicted metal distribution is much too inhomogeneous to reproduce the
observed probability distribution of CIV absorption. These findings suggest
that strong z <~ 6 winds cannot fully explain the observed enrichment, and that
an additional (perhaps higher-z) contribution is required.
