The Donaldson-Thomas invariants of a Calabi-Yau threefold are virtual counts of its coherent sheaves, and are known to be invariant under deformations of its complex structure. Motivic Donaldson-Thomas invariants refine these integers to classes in the Grothendieck ring of varieties, which are no longer deformation-invariant. I will describe some calculations and conjectural formulae for these motivic invariants when the Calabi-Yau threefold is the noncommutative space defined by some simple quivers with potential.