My first thought was like Ted's:  dual H/T 18-core late model Xeons, if you got the bucks.

     On a budget?  How about dual H/T hex-core Xeons with 24GB RAM for $574?  Twenty four render threads.

     Need cheap rendering drone power?  Dual L5520 H/T quad-core Xeons (rack-mountable blade) with 24GB RAM for $355;  as many as you want.  Sixteen render threads.

     Twenty four render threads in a rack-mountable blade:  Dual H/T hex-core X5650 Xeons with 24GB RAM for $461.

     Faster blade with dual H/T hex cores (3.46GHz w/3.73GHz turbo):  Dual X5690 H/T hex core Xeons with 48GB RAM for $1,925.

     Workstation with dual X5690 H/T hex-cores and 48GB RAM for $1,139.

     If you need late model features, a good compromise would be a new core i7 with USB3 mobo and late model GPU(s), backed up with Westmere series Xeon blades/workstations/servers bought used from the enterprise market.  You don't need a rack for blades, by the way;  I started out with them just stacked on a milk crate.  Later, I bought a simple open frame rack.

Poser 12, in feet.  

OSes:  Win7Prox64, Win7Ultx64

Silo Pro 2.5.6 64bit, Vue Infinite 2014.7, Genetica 4.0 Studio, UV Mapper Pro, UV Layout Pro, PhotoImpact X3, GIF Animator 5