A method, apparatus, and computer instructions for changing an operating frequency for a system core logic used to interface to memory in the multi-processor data processing system. A determination is made as to whether the operating frequency should be changed from a default frequency to another frequency. Slave processors are placed in the multi-processor data processing system into a non-transactional mode, in response to determining the operating frequency should be changed from the default operating frequency to the another operating frequency. When the slave processors are in the non-transactional mode, the operating frequency is changed in the system core logic to other operating frequency by the master processor.