I have heard a lot of positive results from OWC on installing the ATI 5770 on a 2006 Mac Pro 1,1 machine. My main questions about this type of install are:
1) would I really benefit from hardware acceleration considering there is a bus speed reduction from using this card on a 2006 Mac Pro?
2) what sort of benchmarks could I expect from implementing openCL on my system?
3) could I run multiple cards to benefit from additional hardware acceleration like openCL?
4) would I be better off looking at a card capable of cuda than openCL?
I primarily do work with graphics, video, programming (various, but often graphics intensive), and day to day office tasks.
a link to the card I am talking about:
http://store.apple.com/us/product/MC742ZM/A