Abstract: Various embodiments of the present invention are directed multi-core memory modules. In one embodiment, a memory module (500) includes memory chips, and a demultiplexer register (502) electronically connected to each of the memory chips and a memory controller. The memory controller groups one or more of the memory chips into at least one virtual memory device in accordance with changing performance and/or energy efficiency needs. The demultiplexer register (502) is configured to receive a command indentifying one of the virtual memory devices and send the command to the memory chips of the identified virtual memory device. In certain embodiments, the memory chips can be dynamic random access memory chips.