new backup build

[flyphish]

I have been floating along with 2 servers running,  no issues for years, thanks Unraid!  In any case, my back up server motherboard died.  It was a standard PC board, nothing special.  However, now the mb is dead, i am looking to replace it.  My primary box is a 36 drive supermicro rig, that does the heavy lifting Plex and such.   So basically I run a bunch of VMs and some communications through this one, ie. openvpn and pfsense.  Plus it backs up the main box.  The question is this.....i want to put a supermicro in it.  However, how new do i need to keep it.  e3-1245v5/6 too much chip for my purpose? I would like to keep it to one cpu.   Am i better off digging up an older x9 vs a x11.   Been out of the hardware game for a bit and playing catch-up.  Thanks in advance.