It was suggested to me by other forum members to repost my previous thread on this subforum to seek better help with my questions: http://forums.macrumors.com/threads...-ati-radeon-hd-5770-x2-on-macpro-5-1.1895954/ There is the original post: I have a Mac Pro 5,1 with a stock ATI Radeon HD 5770. I recently purchased another genuine Apple (not Apple-flashed) ATI Radeon HD 5770 and installed it in the Mac Pro. Both cards are working fully and independently on Yosemite and on Windows 7. I want to now set up the two cards using Crossfire to use for both Mac and Windows (dual boot). My questions: 1. Is it possible to crossfire two stock genuine Apple ATI Radeon HD 5770? Both cards have fingers that are seemingly for the Crossfire bridge connectors. 2. Where do I buy the Crossfire bridge connectors? Does ATI or Apple sell the bridge connectors for 5770? Is the bridge connector different for the different models? 3. I am using the BootCamp driver 5.1.5621 that has built-in ATI Catalyst driver support. Is this sufficient to run Crossfire?