Design and evaluation of an optical CPU-DRAM interconnect

We present OCDIMM (Optically Connected DIMM), a CPU-DRAM interface that uses multiwavelength optical interconnects. We show that OCDIMM is more scalable and offers higher bandwidth and lower latency than FBDIMM (Fully-Buffered DIMM), a state-of-the-art electrical alternative. Though OCDIMM is more power efficient than FBDIMM, we show that ultimately the total power consumption in the memory subsystem is a key impediment to scalability and thus to achieving truly balanced computing systems in the terascale era.