I don't understand why #memory chips are still separated from CPUs. Any #computer programmer can tell you that memory access is slow. We put all sorts of things on the same chip together.
@schizanon A number of reasons, simplifies the CPU design, improves cooling, maximises flexibility to match cpu+ram to use case, no expert on this next one but I think optimal/maximum frequencies differ enough between cpu and ram speeds that trying to match them (for compatibility) would inevitably impede the functioning of one or both systems.
There's a really long answer here which might help ... https://electronics.stackexchange.com/questions/175615/why-is-ram-not-put-on-the-cpu-chip