  We use free boson techniques to investigate A-D-E-quiver matrix models.
Certain higher spin fields in the free boson formulation give rise to higher
order loop equations valid at finite N. These fields form a special kind of
W-algebra, called Casimir algebra. We compute explicitly the loop equations for
A_r and D_r quiver models and check that at large N they are related to a
deformation of the corresponding singular Calabi-Yau geometry.
