Technologies are generally described for systems, devices, and methods effective to dynamically select at least one power supply rail for a router. In some examples, a power control unit may be configured to determine a buffer occupancy level of one or more buffers of the router. In some further examples, the buffer occupancy level may be compared to a threshold value. In various other examples, the at least one power supply rail of the router may be switched from a first power rail to a second power rail based on the results of the comparison.