  Eigenvector 1 (EV1) is the formal parameter which allows the introduction of
some order in the properties of the unobscured type 1 active galaxies. We aim
to understand the nature of this parameter by analyzing the most extreme
examples of quasars with the highest possible values of the corresponding
eigenvalues $R_{Fe}$. We selected the appropriate sources from the Sloan
Digital Sky Survey (SDSS) and performed detailed modeling, including various
templates for the Fe II pseudo-continuum and the starlight contribution to the
spectrum. Out of 27 sources with $R_{Fe}$ larger than 1.3 and with the
measurement errors smaller than 20\% selected from the SDSS quasar catalog,
only six sources were confirmed to have a high value of $R_{Fe}$, defined as
being above 1.3. All other sources have $an R_{Fe}$ of approximately 1. Three
of the high $R_{Fe}$ objects have a very narrow H$\beta$ line, below 2100 km
s$^{-1}$ but three sources have broad lines, above 4500 km s$^{-1}$, that do
not seem to form a uniform group, differing considerably in black hole mass and
Eddington ratio; they simply have a very similar EW([OIII]5007) line.
Therefore, the interpretation of the EV1 remains an open issue.
