GTX 680 or Quadro 4000?

GTX 680 or Quadro 4000?

Can I use both in a Mac Tower?

Will one outperform the other? Will I notice the difference, if so, in what situations?

Not really worried about price difference so much as I am about performance. Or is there anything that is even better within this price range?

Any thoughts are welcomed?

There is another post on this question.
Radman.

Simply: in Resolve, the GTX 680 will outperform the Quadro 4000 in every way, by a wide margin.
The Quadro will do better for other tasks, such as 3D modeling, raytracing, etc.
To (safely) run both simultaneously would require more power than the Mac Pro has, so you'd need an optical bay PSU. But that will give the best performance, given these options, using the Quadro for Resolve's GUI.