Firstly thank you Asgorath for this thread and everyone else for their input, it seems the Mac Pro community can do what Apple can't be bothered to. Although I do resent having to turn my genuine Mac Pro into a quasi hack if I want an up to date GPU.
So, I've read every post in this thread, and have a couple of questions.
I've read in a couple of places that if you care more about CUDA than gaming, then the 580 (+External PSU) or 570 is the best, as Nvidia restricted CUDA on the 6xx series cards to sell more Quadro. But if I compare the two cards, the 580 is listed as having 512 CUDA Cores and the 680 as 1536. Could someone explain how the 5xx series are thought to be better for CUDA as on face value the 6xx series have more?
It seems that with the release of 10.8.3 the Radeon 7970 may be usable to, if this does happen would this be a better choice than Nvidia, not just for GPU performance, but compatibility with a Mac Pro as it will be an official card?
I only use my Mac for Cinema 4D, Adobe PS and AI, which don't use CUDA (I believe) and I know that a new GPU won't speed up my renders. So, I would be happy with any improved viewport performance and am leaning towards a 680, unless anyone recommends the 7970. Either way I'm positive anything will be an improvement on my 4870 (512MB).
I think someone else asked this question, without a response. If it is recommended that on a 2009 Mac Pro an Nvidia card is installed in slot 2, would a triple height card still fit?
That's all, thanks.