I need a bigger better GPU for my 2010 mac pro 3.33 running Sierra and having already tried a GTX 970 with the software I need it for , I know nvidia cards will not work , so it has to be AMD. Unfortunately the Sapphire Pulse 8gb RX580s are rare as hens teeth here in Australia. They can go as high as $600 and I ain't paying that sort of loot for one. Unfortunately I want one to use with Trainz simulator, which isn't optimized for Metal and due to the ability of players to make their own assets, is notoriously hard on GPU's . I want 8gb Vram as I was using a GTX 680 4gb briefly until it died and saw very little improvement over the 2gb model I'm using. I was wondering if anyone has tried the ASUS Radeon RX 580 8gb ROG Strix TOP Edition or the Gigabyte Radeon RX 580 Gaming 8GB in their Mac pros ? I've spent about an hour looking through these posts , plus hours on the net as well and could not find anyone who has one installed and working. Of course i know they may have boot up issues, but given the 8gb Radeon mini gaming card is included in one of the latest e gpu enclosures , i was hoping its big brother might also be a good choice to go for . I'm prepared to update to High Sierra if i have to in order to get this to work even though my copy of CS5 Photoshop will probably give me grief .