I have a 2006 Mac Pro and I'm wondering if CrossFireX is possible on this system. Specifically with two 5770s. My understanding is that CrossFireX requires two PCIe 2.0 16x slots. However, the 2006 Mac Pro only has PCIe 1.x slots, and with two cards, it's only possible to have its slots running at 8x. Does this prevent CrossFireX from working at all, or is it simply a case of it working fine but running at reduced performance? Anyone know?