Optimal system for 4X 2MP BI cam setup?

[agurkas]

Right now I have 4 cameras from my vacation place streaming to my house where I am handling another 12 on the BI setup.
I would like to split off the 4 cams and run them locally. What would be the optimal setup for it?
I've had great success with refurb Dell Optiplex for my home and office, but in both cases, I had dozen plus cameras to handle.

 

[pinko]

I'm using an old i7 -3770k setup. Runs 3x 2mp Cams + plex server. CPU sits around 10-20% under heavy loads( multiple plex streams and transcodes), may momentarily spike up to ~50%.