51GB/s * 8 (octa-channel, not dual channel as you are calculating) is 408 GB/s. Basically the same as the M1 Max. It's not fair to use an off the shelf product

51GB/s * 8 (octa-channel, not dual channel as you are calculating) is 408 GB/s. Basically the same as the M1 Max. It's not fair to use an off the shelf product since even if the RAM is slotted Apple wouldn't use an off the shelf product. Whether they use slotted RAM or not has nothing to do with performance. It's a design choice. For the mobile processors it makes total sense to save space. But for the Mac pro they might as well use slotted RAM. Unless they go for HBM which does offer superior performance.