1. A method of proactive power management in a parallel computer, the parallel computer comprising a service node and a plurality of compute nodes, the service node connected to the compute nodes through an out-of-band service network, each compute node comprising a computer processor and a computer memory operatively coupled to the computer processor, the method comprising: receiving, by the service node, a user instruction to initiate a job on an operational group of compute nodes in the parallel computer, the instruction including power management attributes for the compute nodes; setting, by the service node in accordance with the power management attributes for the compute nodes of the operational group, power consumption ratios for each compute node of the operational group including a computer processor power consumption ratio and a computer memory power consumption ratio; and initiating, by the service node, the job on the compute nodes of the operational group of the parallel computer.