AMD announced some cards oriented toward heavy OpenCL computing: http://www.hpcwire.com/features/AMD-Chases-NVIDIA-with-New-FireStream-GPU-Offerings-97006419.html While the top end card is perhaps a bit of a stretch for a Mac Pro ( weighs in at 255W which just about blows the whole PCI-e power budget) the more modest card is a better fit ( single wide and could be coupled with medium video card ). That's a good match to the Mac Pro. Would have been nice if it supported ECC but gotta crawl before walk. Will be curious if Apple jump-starts this. It is a catch 22. Unless someone steps up and does (or funds) the OS integration work it isn't likely to show up. Not likely to get the software and roll up system vendors making updates to leverage it if not present. Demand isn't going to work from other direction either software folks pulling AMD onto the Mac OS X platform. AMD already has Linux and Windows on their plate to support. This may end up like Inifinband where Apple ignores it and then gets left in the dust when becomes popular in the heavy lifting context. For Apple this would help with problems where users of the GUI app really need a "small scale" rendering farm to do the batch processing work while they continued to do yet another more GUI, immediate interaction based task.