Managing power in a parallel computer, the parallel computer including a power supply and a plurality of compute nodes, the plurality of compute nodes powered by the power supply through a plurality of DC-DC converters, each DC-DC converter supplying current to an assigned group of compute nodes, each DC-DC converter having a current sensor. Embodiments include monitoring, by the current sensor, an amount of current supplied by that DC-DC converter to its assigned group of compute nodes; determining, by at least one DC-DC converter, that the amount of current supplied is greater than a predefined threshold value; sending, by the at least one DC-DC converter to the plurality of compute nodes, a global interrupt, including notifying the plurality of compute nodes to reduce power consumption; and reducing, by the plurality of compute nodes in accordance with power consumption ratios, power consumption of the compute nodes.