I wanted try to all the flavors of edge software (Untangle, Sophos XG, pfSense, OPNsense), and I set out to build one:
Optiplex 3040 (Manual, Specs start on page 41):
-Intel H110 Chipset, supports PCIe v2.0 (Link)
-i5-6500, supports PCIe v3.0 (Link)
-Two PCIe slots (x1 and x16)
Dell i350-T4...