  We consider cones over manifolds admitting real Killing spinors and instanton
equations on connections on vector bundles over these manifolds. Such cones are
manifolds with special (reduced) holonomy. We generalize the scalar ansatz for
a connection proposed by Harland and Nolle in such a way that instantons are
parameterized by constrained matrix-valued functions. Our ansatz reduces
instanton equations to a matrix model equations which can be further reduced to
Newtonian mechanics with particle trajectories obeying first-order gradient
flow equations. Generalizations to Kaehler-Einstein manifolds and resolved
Calabi-Yau cones are briefly discussed. Our construction allows one to
associate quiver gauge theories with special holonomy manifolds.
