Yeah but DDR3 was faster then and still is now - I can't imagine my M4 Mac having a slightly older version RAM would meaningfully affect me, but another 24GB of it (or whatever I have) would certainly be an improvement.
CPUs have L1, L2, L3+ caches too after all.
It probably would. LPDDR5 memory bandwidth on M-series Macs is several multiples of the memory bandwidth available on DDR3 (depending on the exact chip, Pro, Max, etc... 4x to beyond 10x.) The whole system would be much, much slower.
> Yeah but DDR3 was faster then and still is now
USB would be the limiter for both.
They obviously did not mean not literal USB, just a standardized connector across DRAM versions/speeds.
Yeah, sure but... if it's real fast, lets connect SSDs to it and have real fast swap. Whatever it is will be limited to the bus speed. And that's gonna be silly compared to RAM speed.