Yes. My machines each have two HyperThreaded hex core Xeon processors (server/workstation motherboards often have two CPU sockets), so 24 render threads. Open Task Manager (Ctrl+Shift+Esc) and go to the performance tab while rendering; it should show a graph for each core, and they should all be at/near 100% capacity.

Multiply the number of cores by the clock speed to get a value of rendering power. 3.3 * 12 > 3.5 * 8, so the 3.3GHz 12-core would render faster. If one/both processors are HyperThreaded, take that into account, since it effectively doubles the number of cores, albeit the virtual cores may only be about 3/4 the speed of the primary physical cores.

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