Normally, a single point on fermi surface does not influence the transport properties of a system. However there are exceptions to this rule. In this talk we discuss a single band tight binding model where the fermi surface crosses a van Hove point. We show that this van Hove singularity can cause a change in the temperature dependence of the conductivity of the system over a large temperature scale. This behavior extends to all temperature scales if we take additional bands into account which we demonstrate with the specific example of Strontium Ruthenate.