Given a finite quiver together with a finite set of relations, one can ask to determine the irreducible components of the associated representation space for any dimension vector. Inspired by work of Lusztig on spaces of nilpotent representations of preprojective algegras, we tackle this problem using partitions obtained from semicontinuous functions, coming from basic concepts in representation theory. We consider several cases of quivers with relations for which we can determine all irreducible components, as well as their dimensions. If there is enough time, we will consider quivers with relations for which all representation spaces are equidimensional.