Ah. Ok. Modo will have an inbuilt GPU renderer soon, though it's in pretty early stages - AMD pro renderer (already part of Cinema4D ). And once you go GPU rendering it's hard to go back to CPU and even the traditional bottlenecks - Out of core, Idle CPUs will be a thing of the past the way renders are moving, harnessing all the power of the system - GPU+CPU. Based on what you are doing, I think an iMac pro seems to be a good choice. For now.