1. A computer system comprising: a first system memory comprising at least one memory module including volatile storage; a first memory controller coupled to said first system memory and configured to read data from said first system memory corresponding to an address of a current memory request; a second system memory comprising at least one additional memory module including additional volatile storage; and a second memory controller coupled to said second system memory and configured to selectively pre-fetch data from said second system memory depending upon selected address bits of said address of said current memory request.