Volunteer computing projects have been used to make significant advances in knowledge since the 1990s. These projects use idle CPU cycles donated by people to solve computationally intensive problems in medicine, the sciences and other disciplines. It is important to use the donated cycles as efficiently as possible because participation in volunteer computing is low and the number of volunteer computing projects keeps increasing. Task retrieval policies, policies describing when a volunteered computer requests additional work from a server, can have an effect on the number of wasted CPU cycles and consequently, the number of tasks completed by clients. We present the results of simulating different task retrieval policies for clients under realistic conditions, including clients running on computers with one single-core CPU, clients running on computers with multi-core CPUs, and clients running on computers that are put into a power save mode by environmentally conscious owners.