Fault tolerance is becoming an increasingly important issue, especially in mission-critical applications where data integrity is a paramount concern. Performance, however, remains a large driving force in the market place. Runtime reconfigurable hardware architectures have the power to balance fault tolerance with performance, allowing the amount of fault tolerance to be tuned at run-time. This paper describes a new built-in self-test designed to run on, and take advantage of, runtime reconfigurable architectures, using the PipeRench architecture as a model. In addition, this paper introduces a new metric by which a user can set the desired fault tolerance of a runtime reconfigurable device.