Which CPU metrics most important for 3D rendering?

? ?I'm looking to expand our current farm which is about 75 nodes, each with Dual E5-2620's and 32GB of RAM. ?Space is becoming a constraint so we're looking into stronger CPU's and less total systems. ?

I'm having trouble finding which CPU metrics are most important for 3DS Max rendering. ?I'm assuming it's more reliant on cache, cores, and threads than raw clock speed, but I'm not sure. ?Google was little help, as were the Autodesk forums. ?

Regards from a sysadmin who is new to the studio niche,

-Will