N100DC

I've been testing an AsRock N100DC for a bit now with Mesa Ethernet cards and the latency is really good and no read errors after a few days connected to a 7i96s. The latency is good enough for software stepping. It has a serial port on the back so if you're using GS2 component over modbus you're golden. Just be careful that you select the correct case, the first one I got was too short to fit the mother board in.

JT

Nice find, and it does have a parallel port header and an M.2 slot.
But at 146 Euro here, i am skipping it for now, might go back to it later as it uses a single power supply, probably 12V adapter, and not the full ATX power supply.