Note that I can’t think of modem four channel x86. Either they are the usual two channel (two dimms per channel is how four dimm slots are organized) or have way more (Sapphire Rapids, Bergamo)

To map the M2, the base is about the same as most x86 consumer grade, the Pro is about Threadripper, and the ultra is somewhere between single or dual socket Bergamo, at least in terms of memory bandwidth, which is a highly specific metric.