A system and method for optimizing memory bus bandwidth, is achieved by utilization of the memory bus, either by utilizing the idle time of the memory bus, or by prioritizing prefetch requests to exploit the bank structure of the external memory. When a bus master of the memory bus makes a request to access a particular line in a memory device, the memory controller generates a request for accessing a line next to the current line that is requested by the bus master. Data corresponding to the next line is retrieved from the memory device and stored in the memory-controller when the memory bus is idle. The stored data may be served to a bus master upon request for the data. However, the memory bus is not engaged when the data stored in the memory controller is served. Therefore idle time of the memory bus is utilized.