I want to install El Cap on a 2006 Mac Pro 1,1. I did a bunch of research but could not find my answer. I need to upgrade the graphics card from the 512mhz card so El Cap can run. I plan on using this machine to make some 1080p videos in Premier for clients. It had 16gb Ram and the original Xeon dual core processors. Can it do the job? Anyways, I am looking at an AMD Radeon 280X on eBay. It is good priced and pulled from a 2010 Mac Pro. Would it already be flashed for my 2006 MacPro. I really don’t want to flash a card on my own. See it here; https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/192517083973 This Mac was basically free for a friend. Please help!