Four modules with DDR5 doesn't like high RAM frequencies at all. The signal quality degrades too much when using four DDR5 modules. I wrote about this in my
RAM thread under point 2).
You will never reach the DDR5-5600 XMP speed with four modules. On a four-DIMM (four-slot) mainboard, with
two modules, you can already get problems with stability around DDR5-6000.
So you can imagine what will happen with four modules. You will be lucky to reach around DDR5-5000, but most likely you will be stuck in the mid-4000 range.
So on top of the IMC (memory controller), the board itself becomes another limiting factor with DDR5, since the signal quality needs to be so much cleaner now. Often times, the good enough signal quality may only be reached with a two-DIMM (two-slot) board, which eliminates the signal reflections of the empty slots. Once you populate all four slots on a four-DIMM board, it all goes completely down the drain with DDR5, it doesn't like that at all, further demonstrating how much of a "diva" DDR5 is at the moment. The situation could improve with further DDR5 board/CPU/RAM iterations.
So the RAM itself can do DDR5-5600 fine, it's the other components of the memory system causing the limit here: The IMC and the board, with its RAM slot layout / PCB / BIOS, and of course the stress and electrical worsening that four modules cause for the memory system. To have any chance of running DDR5-5600 XMP, you need to use two modules only. To run DDR5-6000+, certainly starting around DDR5-6200 or so, you even need to use two modules only
on a two-DIMM mainboard.
Also, you need to question if you really need 64 GB of RAM, see my RAM thread under point 3). Most people will not need that much unless they use special software that requires it.
