I just had a visit from Dave Pirinelli from MacvidCards.
I have no affiliation with David or MacVidCards, other than I use his GTX 285 with stock MacPro 4.1, octo 2.26 Ghz and Resolve, that I had purchased almost 2 years ago.
He offered to bring various Mac video cards to test with Resolve.
So we had tested:
1. GTX 285 with 1 GB of RAM
2. GTX 470
3. GTX 480
4. Quadra 6000.
All cards ran fine with Resolve. Only GTX 480 required an external power supply. They all showed up correctly in the system profiler, with exception of Quadra 6000 showing 2GB of RAM, instead of 6GB.
GTX 470 and 480 were properly recognized by Resolve. Resolve complained about Quadra 6000, but it still ran fine, as far as I can tell.
I used the Noise Reduction to simulate a heavy GPU load. I used settings of 2 and 3 on the NR to see the playback speed. Lower number requires more number crunching GPU power.
So, here are the findings:
1. GTX 285 NR=2 9 fps NR=3 16fps
2. GTX 470 NR=2 12.5fps NR=3 21fps
3. Quadra 6000 NR=2 12fps NR=3 20fps
4. GTX 480 NR=2 16 fps NR=3 Real time
For my money. GTX 470 is the best value with Resolve. As you can see, this card actually exceeded the performance of Quadra 6000. The overall champ was GTX 480. This is the only card, that was capable of real time performance with the NR. Not too bad, but the external power supply is a bit of a bummer. Not a problem, though with the external enclosure.
Hope this info helps...