The bandwidth is fastest with one single-rank DIMM per channel, and there are four slots and two channels, so you ideally want two single-rank (chips on one sid

The bandwidth is fastest with one single-rank DIMM per channel, and there are four slots and two channels, so you ideally want two single-rank (chips on one side) DIMMs total. It'll get slower with 2DPC (DIMMs Per Channel), and slower still with dual-rank 2DPC. Some people are even seeing instability, with that setup at the slow DDR4 speeds. There aren't any 32GB single-stick DDR5 DIMMs yet, let alone 32GB single-rank single-stick, so if you want 64GB then you're using four sticks of dual-rank 16GB, the worst scenario.