I am curios whether having two or more of these instances on the same machine help using more RAM and more (logical) CPUs.
By default an instance of SQL Server Express would only use 1 GB of RAM and 1 cpu only.
Having a machine with 4 cores and 4GBs of RAM, could 4 instances be better? Or the Express edition would detect this and enforce that all instances would use 1 GB of RAM (summed) and only one core?
I also hear that you can't install more than 16 instances on a machine.. Could this be true?
This isn't a very professional way of working but SSE will support more than 1 core but only one physical CPU, so a single instance will use all 4 of your cores. One instance won't use more than 1GB however but if you really wanted to use 2 instances then they could use 2GB etc. As for the maximum number of SSE instances you could possibly run, well I've never needed to try sorry.