Hi Esther

 Apple sells some for the current and previous gen MacPro's.

 Apple prides itself on the absence of internal incompatibilities with it;s hardware and OS. IE, it always works. And people are discovering that some of the modern cards- DO work in the first Gen Xeon

Since the hardware is fully compatible with PC boards- many people have figured out ways to use then in their intel macs. Apple does not guarantee these boards- but many people are delighted with them.