Off-chip memory systems are currently designed to present a uniform interface to the processor. This paper describes two techniques and specific designs for achieving aspects of proportionality in the main memory system. The first, dynamic and adaptive granularity, utilizes conventional DRAM chips with minor DIMM modifications (along with new control and prediction mechanisms) to access memory with either fine or coarse granularity depending on observed spatial locality. The second, virtualized ECC, is a software/hardware collaborative technique that enables flexible, dynamic, and adaptive tuning between the level of protection provided for a virtual memory page and the overhead of bandwidth and capacity for achieving protection.