A memory subsystem is disclosed comprising at least one memory module, the memory module having a substrate to which a plurality of memory chips is mounted and a voltage regulator, the voltage regulator receiving a power supply signal from a system power supply and outputting two or more power signals, each power signal providing a different, regulated voltage, which regulated voltages are each routed to each of the memory chips; and a redundant voltage regulator external to and not mounted on the memory module and configured to output two or more power signals, providing external different, regulated voltages which are the same voltages as the voltages output by the voltage regulator on the memory module, and supplying the two or more signals to the memory module.