> or are their others out there that are supported that are just as good
Nope, unfortunately Apple OS X 10.8.2 Mountain Lion doesn't support much of anything (as of right now) and it's been like "pulling teeth" trying to get graphics card (hardware) support in the latest Mac OS X.
Unfortunately, as it stands, you'd be forced to just put the graphics cards into your Apple Mac Pro, and then boot directly into Windows because Mac OS X really doesn't support any decent hardware at the moment.
The four best graphics cards out at the moment are the Radeon HD 7970, Radeon HD 7990, GTX 680 and GTX 690.
For the price, the Radeon HD 7970 is the best graphics card (for the price). With 3GB of DDR5 memory (3GB of texture memory) and it's quite a bit lower price than a GTX 680 (with only 2GB of DDR5). So the price/performance of a Radeon HD 7970 GHz Edition really can't be beat at this point in time.
Unfortunately, who knows how long we'll have to wait to get graphics drivers support in OS X 10.8.2 to support the latest Radeon HD 7970 GHz Edition graphics cards.
I have 27 Apple Mac Pro's (at the office) and four Apple Mac Pro's at home, and I have Radeon HD 7970's in all of them. Great graphics card, but unfortunately I'm still waiting on Apple to release graphics drivers for the Radeon HD 7970 GHz Edition.
In the meantime, I'm forced to just boot directly into Windows if I want to use the graphics cards.
It's quite sad, but Apple is quite a bit behind the PC sector, and I'm not sure if they'll ever catch up. I was shocked that Apple release a "2012" Apple Mac Pro that didn't even have USB 3.0, or PCIe 3.0, or native Blu-Ray 3D support, or even a 4K2K 3D Blu-Ray burner (128GB BDXL disc support). The 2012 Apple Mac Pro didn't even have Thunderbolt?
I'm not quite sure what is going on over at Apple, but the whole Apple Mac Pro product development team really needs to be fired, and Apple needs to get a few engineers from EVGA and start using an EVGA SR-X motherboard with seven PCIe 3.0 slots, and dual processor sockets, and just build a nice brushed aluminum EATX case for standard motherboards, so that Apple Mac users can start using decent COTS (commercial off the shelf) hardware.
Apple should focus more on Apple OS X development (updating hardware/graphics drivers) to support a much wider range of hardware, and begin building Apple Mac Pro's based on the much faster and much more powerful PC hardware that is available.
It's sad that it might be another 3-5 years, before Apple can even compete with a PC motherboard from 2010.
See here: http://www.youtube.com/watch?v=D0qVZz-ot6k
For the price that we are paying for an Apple Mac Pro, we should actually get decent hardware instead of $600-$800 worth of hardware and paying a huge $2,400+ price (which is nothing more than record 400% to 500% profits for Apple).
Apple should be offering us better hardware (the latest and greatest hardware) at a much more affordable price (around $1,800 with an SR-X Motherboard and dual-socket Xeon's).