[formerly_proven]

Is the memory controller aware of unused pages in physical RAM that thus can be safely skipped during refresh? That would surprise me. In stand-by the self-refresh mode is used, and I believe partial refresh is only supported by the low-power (LPDDRx) standards and is very coarse-grained.

[vlovich123]

No. What I heard proposed was just at the DIMM level. The memory controller has no concept of memory usage.