On Wed, Mar 28, 2018 at 06:35:59PM -0400, D. Hugh Redelmeier via talk wrote:
My Sun 3/60 has 24 slots. But the largest memory module that it will accept is 1MiB (note: not 1GiB). So more isn't always better :-)
As memory systems get faster, fan-out and signal path length matter more. So 4 is apparently the limit for "unbuffered" memory on one PC memory bus these days.
The limit is 2 these days. But dual channel makes you have 4 slots on basic systems (Core i9 level machines have 4 channels and hence 8 slots).
If you have multiple processors on a motherboard, they probably have a separate bus for each processor so you get 4 slots per processor.
Well the CPUs that allow that these days are now at 6 memory channels per CPU (ie the Xeon Silver line). Putting 1.5TB ram in a server seems to be perfectly doable these days, if you have a lot of cash. -- Len Sorensen