  We investigate numerically the Princeton magneto-rotational instability (MRI)
experiment and the effect of conducting axial boundaries or endcaps. MRI is
identified and found to reach a much higher saturation than for insulating
endcaps. This is probably due to stronger driving of the base flow by the
magnetically rather than viscously coupled boundaries. Although the
computations are necessarily limited to lower Reynolds numbers ($\Re$) than
their experimental counterparts, it appears that the saturation level becomes
independent of $\Re$ when $\Re$ is sufficiently large, whereas it has been
found previously to decrease roughly as $\Re^{-1/4}$ with insulating endcaps.
The much higher saturation levels will allow for the first positive detection
of MRI beyond its theoretical and numerical predictions.
