So current server is a 2012 Mac Mini, planning to replace it with a newer one just due to how my setup works (8U portable box, 14" depth and already have dual Mac Mini 1U server mount hardware). All computers/devices that currently interface with this box are also Apple-based.
What I mean by fully saturated is that currently if 4 computers are passing data over the network to the server at the same time, Disk I/O is only at about 70% usage, but the RAM is sitting at 100% utilization and each machine cannot reach past 80-90MB/s each. When one machine is passing data, I can hit 122MB/s out of the theoretical 125MB/s.
The 2018 Mini has R/W of around 1500MB/s. The processor would be a 6-Core i7-8700B. Planning on buying refurb model with base 8GB of RAM and upgrading post-purchase with RAM that doesn't cost an arm, leg and Lance Armstrong's left testicle.
The server has two purposes:
A web server that currently interacts with 10 devices at the same time, but could be going up to 30-40+ concurrent users with the planned changes in how we're going to be operating (clients on their own devices while at an event).
The main repository that the cameras connect to via ethernet (Canon 1DX's) which also resizes files using custom software which I've written. In a three day event it can be resizing and organizing 20-30K images.