Synchronized phasor measurement units (PMUs) are becoming a key element of monitoring, protection, control, and state estimation applications in power systems and are the basis for the implementation of wide area monitoring systems. This paper investigates the possibility of using a software-only precision time protocol synchronization method to synchronize different PMUs inside the same substation and how this synchronization impacts the state estimation. In this context, as a case study, the output data of the PMUs have been used to estimate the state of a portion of real power system. A laboratory experimental setup has been built to evaluate the performance achievable with the proposed synchronization solution. The results thus obtained are discussed in terms of stochastic performance.