Originally Posted by hmm
It's unlikely that either of those will use the gpus to render anything other than what you see on screen during scene navigation. Offline rendering using gpus only comes up in a few places. I know of iRay (built into mental ray), Octane, and whatever pre-beta thing Blender uses. Some others use gpu rendering for draft renders, but the finals are always done on cpu. The typical issues with gpu based rendering are lack of maturity in feature sets and limitations due to things like the amount of ram available.
I should have been clearer.
I had asked about the new MacPro and whether it would be good for rendering, or whether might be better to set up a small render farm (say an 8-core MP versus 2 quad-core machines or even 3 or 4, giving more cores than the single MP (I assume the 12-core will be out of my reach). I am of course worried about the minis and heat.
The answer was: it's not known yet. Though a multi-core machine usually will be faster than a farm of the same core count, it depends on the motherboard of the machine as to how good it will be. He pointed out the 2009 MP as an example of an 8-core machine that was actually quite slow at rendering, due to the layout of the board or something technical that I can't grasp. The apps do not utilize the GPU for rendering.
He suggested waiting to see how the new MP does in real use and then decide. They might actually get one and be able to test it.
As my current iMac is pretty good I am not in a hurry.